Abstract: According to the structure of the parachute and the force characteristics in inflation process,using a flat circular parachute as a prototype,the coupled model of computational fluid dynamics and structural dynamics is set up in the canopy inflation process.Quantitative measurement for flow field around has been carried out in the full state using seven-hole probe,and the test results and calculation results are analyzed comparatively,obtaining that the two topology structures are very similar,and the differential pressure coefficient also has an insignificant difference,so the mathematical model used is reliable.On this basis,the numerical simulation and analysis are carried out for the flow field in the whole inflation phase,in order to learn more about canopy shape changes and the flow field changes in internal and external canopy during the entire parachute opening process.The results show that:（1） In the initial inflation stage,canopy shape of expanded part remains relatively smooth and straight,rather than flared.In the main inflation stage,the air gathers at the top of the canopy at first,so that the top of canopy gets expanding,and then expansion part extends to the canopy bottom until totally full.（2） When the canopy vent is opened by airflow,structure porosity of canopy will have a significant impact on flow field.However,from pressure coefficient changes in internal and external canopy of view,porosity has less significant impact on the stagnation pressure within canopy but has more significant impact on the outflow of canopy structure,thus the pressure in outer surface of the canopy would be affected rather largely.（3） For such circular flat parachute with a vent,when the canopy inflated and opened,air separation appears in the canopy tail,then two vortexes forms at the opposite rotation directions in a vortex region.And,with the expansion of canopy diameter,the separation zone gets expanding,the shear zone area of the mainstream to the vortex region increases,so a lateral vortex of two ones in the vortex region increases,and the inner one is squeezed to the region near to parachute top.