Abstract: KLA G200 nanometer indentation instrument was used to conduct high-temperature indentation tests for 18CrNiMo7-6 alloy steel at different temperatures, and the load-depth curves of the material at different temperatures were obtained. The load-depth curve was analyzed using the contact stiffness-contact depth/Oliver-Pharr analysis method to obtain the hardness and elastic modulus of 18CrNiMo7-6 alloy steel at different temperatures. Numerical fitting provide expressions for the changes in elastic modulus and hardness with temperature. The results show that the hardness of 18CrNiMo7-6 alloy steel shows a decreasing trend with the increase of temperature, and the decreasing trend of hardness gradually increases with the increase of temperature. As the temperature increases, the elastic modulus of 18CrNiMo7-6 alloy steel also shows a decreasing trend. In the range of 250-300℃, the elastic modulus of 18CrNiMo7-6 alloy steel shows a significant decrease,and the elastic modulus decreases relatively smoothly with temperature in the range of 300-350℃. After exceeding 350℃,the elastic modulus of the alloy steel rapidly decreases again. The evolution of the elastic modulus of the alloy steel with temperature exhibits a distinct segmented characteristic. The study such as hardness and elastic modulus of 18CrNiMo7-6alloy steel at different temperatures is helpful for further analysis of material properties.