Abstract: The core technique of online trying is 3D clothes simulation which always uses the finite elements methods in present，and it doesn’t meet the demand of online trying for it costs a long time.A new fast 3D garment simulation method is proposed based on the knowledge of clothes design and draping.This method uses Bezier curves to simulate garment pieces which are gotten according to garment design knowledge，then maps the texture of the garment on the curves，and the 3D model of the garment is achieved.Experiments show that the new method can simulate the real 3D effect of garments well and quickly，and it can satisfy the needs of online trying.