Abstract: The values of strength and elongation of 10CrNi3MoV steel were obtained by thermostatic tensile test at temperature from room temperature to 1000℃.At the same time, the phase transition temperatures A_c1 and A_c3 of the steel were tested by thermal expansion method.The results show that the 10CrNi3MoV steel performs superplasticity and has elongation more than 100% at 720 ℃~750 ℃, reaching up to 123.5% at 720 ℃, which is slightly higher than that at A_c1 temperature.