At present, the roll temperature control method of the magnesium alloy sheet rolling process is simple and accurate, which has a serious influence on the shape, thickness and crack. So adopting the method for fluid circulation to control temperature, using fluent software to simulate the fluid-solid coupled heat transfer process and verifying by experiment, then giving the heat transfer trends and laws. The results showed that heating the roll by this method, the surface temperature distribution is more uniform, the maximum temperature difference between the edge and the middle is 6℃, and fluid temperature and velocity have little effect on it; At different fluid temperature and velocities, the temperature of the roll rises with trend of decreasing rate, and when the fluid temperature rises and the velocity increases, the temperature rise of the roll becomes faster, the effect of the fluid temperature on the roll temperature rise is greater than the fluid velocity; The relationship between the temperature of the roll surface and the time is obtained under different heating conditions; The roll surface temperature drop has a period of extension when the roll is stopped heating, the higher the temperature, the longer the extension; There is an error between the simulation results and the experimental results in the roll temperature rise stage, fluid temperature increases, the error becomes larger, the roll temperature increases, the error also becomes larger, the maximum error is 16.16%, the results are consistent, indicating that the model can correctly represent the heat transfer process of the fluid heating roll.