Abstract: Taking a GCr15 bearing steel as the research object, the high temperature tensile test at different temperatures was carried out by thermal simulation testing machine. The high temperature thermoplastic curve of the test steel was drawn, and the brittle temperature range was found. The fracture morphology of GCr15 bearing steel was observed by scanning electron microscope, and the microstructure near the fracture was observed by optical microscope. The high temperature mechanical properties of GCr15 bearing steel were comprehensively studied. The results show that there was only the third brittle interval in the test temperature range, which was 600—850 ℃. The plastic range of the test steel was 900—1 250 ℃. In actual production, the temperature in the plastic range of 900—1 250 ℃ should be selected to straighten the test steel, which could reduce the number of cracks.