To study the aerodynamic performance of the parafoils with different platform geometries, this paper establishes numerical model of steady flow around parafoils during its glide phase. The influence of the trailing edge shape of parafoil on the flow field structure and aerodynamic characteristics under steady descent is analyzed, and the influence of the trailing edge swept forward angle on the aerodynamic performance is investigated on the basis of this study. The results reveal the following conclusions: the swept-forward parafoil has a reduced pressure at the leading edge of the upper surface, which is conducive to the reduction of drag coefficient due to pressure difference and the best aerodynamic performance, so that trailing edge with forward-swept shape is preferred for parafoil design. With the increase of swept angle, both the lift and drag coefficient decrease first and then increases, and the lift drag ratio increases first and then decreases. The flow separation increases with the swept angle, which leads to increased drag due to pressure difference, as a result, the lift drag ratio decreases. Considering the flow field structure and aerodynamic characteristics, the forward-swept platform shape with swept angle 6° can improve the aerodynamic performance best. This paper can provide some reference for the design of high gliding parafoils.