In this paper，based on analysis of parafoil opening properties，two-dimensional opening model of parafoil is presented. canopy radial equation of motion is established. At the same time. parafoil system is assumed to be a two-particle-elastic rod model，then the equation of motion for parafoil system, canopy, and payload is derived. Finally，parameters such as filling time, shock force, inflow velocity, etc. are obtained using computer simulation. The simulation program can be used in some parafoil design.