Abstract: The effects and mechanism of different thermo-mechanical treatment on the high temperature resistance softening performance of Cu-0.31Cr-0.19Zr-0.03Si (mass%) alloy were studied by optical microscopy,transmission electron microscopy,EBSD and Vickers hardness tester. The results indicate that the introduction of pre-aging process and the increase of the amount of cold rolling pressure increase the softening temperature of the alloy. This is related to the strong interaction between the second-phase particles internally precipitated after pre-aging and dislocation in the subsequent annealing process,which hinders the recovery and recrystallization behavior of the alloy. The experiment conducted on the peak aged samples reveals that the annealing softening of the peak aged Cu-Cr-Zr-Si alloy is mainly caused by the coarsening of the second phase particles in the temperature range of 400~640℃. In the temperatures range of 640~720℃,the softening of the alloy is attributed to the combined effects of second phase coarsening,recovery,and recrystallization,where recrystallization softening is the dominant factor.