The invention discloses a high-pressure high-temperature fretting fatigue testing machine, which can be used in a fretting fatigue test in high-pressure high-temperature water, steam or liquid environments. A normal force loading device adopted in the testing machine only needs to adopt a small load linear motor to realize constant normal force loading on a sample, compensates a force value losing after abrasion occurs between a clamping pad and the sample in real time in the whole testing process, can remarkably improve load control and measuring accuracy, and obtains stable normal force loading force value, thereby improving the integral testing accuracy of the fretting fatigue testing machine.