At present, the roll temperature control method in the magnesium alloy rolling process is inaccurate, which has a serious influence on the shape, crack of the sheet. The temperature control of the roll is carried out by means of fluid circulation, using FLUENT software to simulate the fluid-solid coupled heat transfer and verifying by experimental results. The results show that the roll heated by this method the surface temperature distribution is linearly distributed, and the temperature difference between the edge and the centre is in the range of 3-7℃, the effective roll interval accounts for 85%-100% of the total length of the roll, and the fluid temperature and velocity have little effect on it. At different fluid temperatures and velocities, the roll temperature increases with the decrease of decreasing rate. The relationship between the roll surface temperature and the time is obtained under different heating conditions in this study. The simulated values of the average roll surface temperature agree well with the experimental values, the maximum relative error is 6.29 %, which shows that the model can predict the average temperature of roll surface accurately, and as part of the magnesium alloy plate rolling model, it is conducive to the isothermal control of the roll in the rolling process and realizes isothermal rolling control of magnesium alloy plate.