During the flight of the aerospace structure， the temperature and strain amplitude， etc. will change significantly. In order to study the effect of service environment on damping， the internal damping of Mg-6Gd-3Y-0.5Zr magnesium alloy and ZL114A aluminum alloy with the variation of service environment were studied by using DMA tester. The results show that the damping of both Mg-6Gd-3Y-0.5Zr and ZL114A materials gradually increases with the increase of strain amplitude， and under the same amplitude， the damping performance of Mg-6Gd-3Y-0.5Zr is better than that of ZL114A. In addition， the damping of both materials increases with the increase of temperature. The average damping values of Mg-6Gd-3Y-0.5Zr and ZL114A alloy at 330℃ are 2.1 and 1.3 times that at 30℃， respectively. It can be seen that Mg-6Gd-3Y-0.5Zr alloy is more sensitive to temperature rise， when the structure temperature rise is large， its damping should be considered as a variable.