Abstract: TRIP 590 and TRIP 780 steel were pre-stained by tension with strain of 5%, 10% and 15% respectively. The effects of tension pre-strain on retained autensite content and mechanical properties were studied by static tensile test and scanning electron microscopy. The results show that the content of retained austenite in steel reduced and transformed to martensite with increase of the pre-strain, the tensile pre-strain increased tensile strength and elongation of the steel. Strength increased obviously, but ductility changed a little with increase of pre-strain.