Abstract: Based on the comparative analysis of calculating methods of fracture strain using small punch test, the Chakrabarty model was chosen to calculate the fracture strain. The relationship between the fracture strain and the central deflection was expressed as a quadratic polynomial function. The fracture strain of the domestic A508-3 steel was calculated at different temperatures by applying this function. The result indicates that the fracture strain decreases with the experiment temperature. The reason of the fracture strain changing with temperature was also discussed.