Since experimental measurement data related to the complex flow fields surrounding helicopters are difficult to obtain, this study employed the CFD methods in combination with the sliding mesh and dynamic mesh techniques to perform numerical simulations of the dynamic flow fields generated by helicopter take-off and landing. In the present research the finite volume method combined with sliding and dynamic mesh techniques have been used to simulate the flow field around a moving helicopter, and then to examine how complex dynamic flow fields affect the safety of helicopter's take-off and landing. The proposed research methods could not only reveal the flow physics during take-off and landing of helicopters, but also provide critical data for their safety design which would benefit the development of domestic helicopter industry.