Abstract: The temperature field and stress field of magnesium alloy parts can obtain accurate simulation results, only the correct surface heat transfer coefficient h is obtained. The temperature change of the square magnesium alloy specimen during the heating and cooling process of solid solution heat treatment was measured experimentally. By using the lumped heat capacity method（LHCM）, the surface heat transfer coefficient of the sample during heat treatment was obtained. The results show that, the surface heat transfer coefficient of magnesium alloy reaches the maximum value of 50.15 W/（m²·℃） at about 150 ℃ during the heating process of solid solution heat treatment, and then the surface heat transfer coefficient gradually stabilizes. During the cooling process, the surface heat transfer coefficient reaches the maximum value of 33.92 W/（m²·℃） in the initial stage of heat transfer, and then decreases with the decrease of temperature. Taking the obtained heat transfer coefficient as the boundary condition, the solid solution heat treatment model of magnesium alloy specimen is established by ABAQUS finite element software to calculate the temperature change of the specimen. The maximum temperature difference between the calculated results and the measured data is 6.39 ℃, which can verify the accuracy of the obtained surface heat transfer coefficient.