Abstract: With employment of the X-ray diffraction technique,the influence on chemical sensibility of the 304 metastable austenitic stainless steel by its strain induction of martensitic phase transformation. Relevant tensile test made at liquid nitrogen temperature reveals that C,Mn,Cr and Ni are changed from the upper limit of the range as specified in the applicable standard to the lower limit thereof,while martensitic phase transformation tendency is significantly enhanced,and work-hardening is obviously increased. The strain-reduced α'-martensitic phase transformation tendency is very sensible to the contents of elements C,Mn,Cr and Ni. Therefore it is the way for preventing occurrence of martensitic phase transformation to optimize the contents of these elements.