Introduction: the article is devoted to the study of the motor sphere of preschoolers with mental retardation. The issues of complex diagnostics of physical development, motility and psychomotor children of children with mental retardation in comparison with their normally developing peers are considered. Disorders of motor development of preschool children with mental retardation are not clearly expressed, but, to a large extent, are the cause of their lag in cognitive, verbal, and social development. Special motor disorders of these children are most often the result of early intrauterine minimal organic lesions of the central nervous system. In the early stages of development of such children, disorders of muscle tone are observed, pathological tonic reflexes take place, all stages of motor development in infancy are delayed evenly. The combination of these three components results in special disturbances, which are characterized as motor ones. In children with minimal organic pathology, quite often, especially in children with mental retardation, the frontal brain regions are formed very slowly, namely, they are responsible for creating an action program and monitoring it. n this case, the child is not able to build a scheme of the motor act, does not understand what should be the movement. The reason for the difficulties in this case is not a violation of muscle tone, but a disturbance in the cerebral cortex: the child does not understand how to perform the action. In this case, there is a psychomotor disorder. These two groups of motor disorders in children with mental retardation determine the two systems of work to overcome them. There is a third group of disorders - a mixed form, when a child has both motor and psychomotor disorders. The direction of work to overcome motor disorders in children with mental retardation will depend on the nature of the disorders: motor, psychomotor, and mixed. Thus, motor developmental disorders of children with mental retardation may have a different nature, it is necessary to carefully study the characteristics of the motor sphere of these children and implement a differentiated approach to overcoming its disadvantages. Results of the research: the article presents the results of the study of the motor and psychomotor functions of preschoolers with mental retardation, indicators of their health and physical development. A comparative experimental study of the characteristics of the motor sphere of preschoolers with mental retardation and their peers who attend mass groups of the kindergarten allowed to draw some conclusions about the specific shortcomings of the motor development of children with mental retardation. Most children with mental retardation have quite serious impairments in their state of health, are lagging in physical development: they have disproportions in their height and weight, reduced muscle strength in their hands, and insufficient lung capacity. Motor skills do not meet age norms: speed and power characteristics of movements, dexterity and coordination abilities are most reduced. Indicators of psychomotor development, especially the dynamic and spatial organization of movements, are lower than those of peers who attend mass groups in kindergarten. These deficiencies are the result of early organic damage to the central nervous system or its functional immaturity. As a result of studying the state of motor skills of children according to N.I. Ozeretsky revealed some important facts: when performing certain tests (for simultaneity of movements, speed of movements, dynamic coordination of movements) and children with mental retardation, and children from large groups showed equally poor results. This indicates a general trend of deterioration of the motor development of modern children, especially those living in the megalopolis. As part of the neuropsychological research, three groups of children with mental retardation in terms of the development of movements and actions were identified, which can serve as the basis for the implementation of a differentiated approach during remedial work. The application of the method of age cuts allowed to conclude that there is a certain positive age dynamics in the formation of motor and psychomotor children with mental retardation, but there is a difference in the sensitive periods of motor skills formation in children with mental retardation and children with normal development. If in normally developing children, at the age of five, the basic motor skills are practically formed, then in children with mental retardation they are formed only by six to seven years and later. Discussion and conclusions: the article proposed a diagnostic program for studying the characteristics of the motor sphere of preschoolers with mental retardation. Comprehensive diagnostics of the motor development of children with mental retardation is necessary to take into account the individual characteristics of children in the organization of physical education and to implement a differentiated approach in physical education and other motor exercises. Based on the characteristics of the contingent of children with mental retardation, the following system for diagnosing motor development was proposed: an individual assessment of the physical development and functional state of the organism of children of preschool age; assessment of children's physical fitness; study of children's motility using metric tests N.I. Ozeretsky; study of the characteristics of the psychomotor development of children using neuropsychological tests for the study of movements and actions adapted for preschool children with mental retardation. Thus, a combination of qualitative and quantitative assessment of psychological and pedagogical data on the level of development of the child’s motility, dynamic observation and comprehensive neuropsychological research allows most accurately and fully assess the overall psychophysical development of the child, the state of his motility and psychomotor system, predict future development and determine the best ways psychological and pedagogical correction.