_{:The change rule of friction and thermal properties of the alloy after thermal cycling was study by internal friction method combined with DSC, SEM and XRD. The change rule is that the alloy’s internal friction and DSC peak shift to high temperature when experiencing an increasing number of thermal cycles.The results show that this variation is attributed to the occurrence of Spinodal decomposition of the alloy, which formed Mn rich and Cu rich areas.We combine the mechanism of microstructure analyzed the internal friction peak .We calculated the activation energy(Ea) and the pre-exponential factor of relaxation (t0) of the low temperature side internal friction peak. Ea=0.66 eV(heating), Ea=0.74 eV(cooling),t0=1.4×10-15s(heating),t0=3.2×10-18s(cooling). Using the peak separation method to isolate the internal friction peak,which is caused bySmutual coupling of martensitic transformation and antiferromagnetic transition. According to the fitting results, the experimental phenomena can be explained reasonably.}