Given the ever-increasing of the older adults population and in order to achieve healthy and active ageing goals and improvement in the cognitive function and sleep quality in older adult, this study aimed to evaluate the effect of cognitive training program on improving cognitive function and ageing-related sleep quality in community-dwelling elderly in Iran, in 2018. This was an experimental study. The sample comprised 420 older adults who were a member of the comprehensive health center in one of the southern cities of Iran. 164 had a cognitive problem and sleep disorder, of whom 108 were selected by the available method and based on inclusion criteria. Participants were randomly allocated to an experimental group (n=54) and a control group (n=54). Experimental group samples were undergoing the intervention for two months. Data were collected using MMSE questionnaire, Pittsburgh sleep quality, insomnia severity index and Clinical Dementia Rating Scale (CDR). Data were collected one month before-and-after the intervention. Data were analyzed using SPSS software. There was no significant difference between the mean score of cognitive function and sleep quality in both the intervention group and the control group before the intervention ( >0.05). At the post-test, the mean (SD) of elderly adults' cognitive function in the intervention and control groups were 2.7 (1.3) and 3.44 (1.7), respectively ( =0.017). Moreover, the mean (SD) of sleep quality in older adults in the intervention and the control group was 6.76 (2.3) and 9.25 (2.36), respectively ( <0.001). Given the obtained results in the current study the cognitive training promotes cognitive function and sleep quality in older adults. Therefore, since this program is effective, low-cost and applicable, it can be used to improve cognitive function and sleep disorder in the older adult population.