Abstract: In order to solve the problem of drape defaults which usually appear on the surface of parts, pre-stretching experiments were done to investigate the effect of prestretching deformation on the yield platform of high-Si, low-Cr TRIP steel, and the microstructures were characterized by TEM before and after the tensile process to find out the forming mechanism of the yield platform. The result shows that the length of the yield platform always decreases with increasing prestretching deformation and disappears at the point of 1.0% prestretching. The specimens with more stable austenite possess shorter yield platforms under the same deformation condition. Yield platform formation of TRIP steel results from Cottrel atmosphere and stress relaxation-induced austenite transformation.