This study investigated the fretting wear behavior of the nuclear power material Inconel 690 alloy. An improved PLINT high-temperature fretting tester was used on an Inconel 690 tube against a 1Cr13 cylinder at different temperatures (25 ℃ and 300 ℃) under alternating load conditions. The fretting-wear mechanism and the kinetic characteristic of Inconel 690 alloy were analyzed. Results showed that the fretting running behavior was closely related to the normal excitation frequency. In parallelogram shaped Ft– D curves, the friction fluctuates periodically, and accordingly the fretting was running in the slip regime. The steady-state friction force at room temperature in air was higher than that at 300 ℃. Moreover, the damage behavior of the fretting for Inconel 690 alloy strongly depended on the normal load, displacement amplitude, temperature, and excitation frequency in atmospheric environment. A superposition effect of fretting wear behavior was discovered because of the combined effect of alternating normal and tangential forces; thus, delamination became more significant. Abrasive wear and delamination were the major mechanisms in Inconel 690 alloy at room temperature in ambient air. The dominant mechanisms at 300 ℃ were the abrasive wear, oxidation wear, and delamination.