Magnesium alloy sheet rolling has special control requirements on the temperature of the work rolls, so in this paper, the temperature of the rolls was controlled by fluid-solid coupled heat transfer. Based on the finite difference method, a differential model for the heat transfer process of roll and thermal oil was established, which was complemented by the corresponding experimental verification. A fluid-solid coupling heat transfer model was also established by FLUENT, which gives the roll temperature rise curve and the distribution of surface and cross-section temperatures during the heat transfer process. The results show that the temperature near the operating side of the roll is the highest, the temperature decreases gradually from the operating side to the driving side, and the temperature difference range between the operating side and the driving side is 5~12℃, which is almost unaffected by the fluid temperature and speed. The maximum temperature difference between the inner wall and the outer wall of the roll is 6℃, so it can be considered that the radial temperature distribution is even. Under different fluid temperatures and velocities, the temperature of the roll rises at a decreasing rate, and when the fluid temperature rises and the velocity increases, the temperature rise of the roll becomes faster. After the heating for the roll is stopped, its surface temperature does not immediately begin to drop and remains for a period of time, about 5~8 min, and the temperature and speed of the fluid have a small effect on the extended time. The calculated values of the average roll surface temperature agree well with the experimental values, and the maximum relative error is 8.3%, demonstrating that the finite differential model is effective, and can be used as part of the magnesium alloy plate rolling model.