Abstract: Microstructure transformation of Fe-13Cr-5Ni martensitic stainless steel during continuous heating was investigated by optical microscopy, transmission electronic microscopy, X-ray diffraction, and microhardness testing. Experimental results show that at the heating rate of 10℃·s^-1,there is an austenite memory phenomenon after heating to the austenite phase region and quenching to room temperature. Austenite tends to nucleate and grow at lath boundaries in an acicular shape, which has Kurdjumov-Sachs (K-S) orientation relationships with the parent phase. Furthermore, heating to different temperatures in the dual-phase region and quenching to room temperature, the amount of retained austenite in samples firstly increases, gets to the peak at 650℃, and then decreases with the increasing of annealing temperature. This trend is coincident with the trend of micro-hardness of the same samples.