Display omitted •Protective performance of ACH and full-covered helmet under blast wave were quantitatively analysis by the degree of cranial injury.•ACH does not provide blast protection and may even slightly aggravate cranial injury.•Fully-covered helmet can reduce the brain acceleration, strain, displacement, pressure, von-Mises stress and energy absorption.•The lighter fully-covered helmet can effectively reduce head injury by 35%, especially by reducing acceleration, strain and pressure. Blast traumatic brain injury (BTBI) is the major type of injury, existing helmets are mainly designed to resist bullets and fragments, so it is necessary to study the explosion- proof performance of helmets. In this study, the validated finite element models including head, Advanced Combat Helmet (ACH), fully-covered helmet based on the prototype of Iron Man helmet were used to establish the blast wave-helmet-head fluid–solid coupling model, dynamic responses such as blast wave flow field pressure, skull stress, brain tissue pressure, displacement and energy absorption were obtained through simulations. Quantitatively analyzed the protective performance of helmets show that wearing ACH can’t reduce the severity of brain injury, but rather increased about 5% compared to without wearing helmet. Wearing fully-covered helmet with same thickness as ACH can reduces the degree of brain injury by about 5%. Fully-covered helmet with same weight as ACH provides better protection, which can reduce the degree of brain injury to 65% than without wearing helmet. Research show that optimizing the shape and thickness of helmet can greatly reduce the brain injury, lighter fully-covered helmet can provide better protection for the brain under blast wave environment. The results can provide reference for new design of helmets.