In both traditional transverse and longitudinal stretch forming processes, the movement of clamping mechanism is inconsistent with the deformation of sheet metal in transition zone which leads to forming defects, such as unconformability of sheet metal to forming die, uneven deformation, wrinkling or even fracture. In order to reduce the manufacturing cost, improve the conformability of sheet metal to forming die and obtain high precision of formed parts, the research on sheet metal flexible stretch forming is of great academic value and wide application prospect. The review on forming die flexibility and loading mechanism flexibility in sheet metal flexible stretch forming was introduced.The forming principle, device buildup and forming characteristics of multi-roller and multi-gripper flexible stretch forming processes were elaborated emphatically.The effects of the main process parameters such as the transition length and loading path of sheet on forming quality were analyzed concretely, and the distributed force/displacement loading stretch forming processes were described briefly. Finally, develop directions of sheet metal flexible stretch forming were pointed out.