In order to study the finite mass inflation dynamic behavior of parachute at an airdrop mission, the penalty coupling algorithm and the adaptive mesh technology were used to analyze the fluid-structure interaction characteristics between the flexible parachute structure and the surrounding incompressible flow field. The three dimensional dynamic opening profiles of parachute were numerically simulated and some parameters of parachute system like dropping velocities and drag coefficients were obtained; the influences of initial dropping velocity on filling time and drag area were compared; the trajectory was validated by the experimental data from airdrop tests. The computation results show that this method can efficiently simulate the dynamic characteristics of finite mass inflation in parachute system. The simulation results coincide with the test results.