In order to improve the performance of back drawing type of flexible multi-gripper stretch forming machine used for double-curvature metal sheet forming, back and down drawing type of flexible multi-gripper stretch forming machine was designed by finite element method (FEM), which has simple structure and cheap cost. The FE model of flexible multi-gripper stretch forming was established, and extensive numerical simulations of spherical parts for two kinds of flexible stretch forming machines were carried out. The variations of stress, strain, thickness and springback value of spherical parts for two kinds of drawing modes were analyzed. The numerical results show that the quality of spherical parts formed by the back and down drawing type of stretch forming machine is better than that by the back drawing type of stretch forming machine. This work provides a machine for developing the technology of stretch forming.