Abstract: A virtual thermal test system was built through the co-simulation using Simulink and Comsol to realize the complete virtualization of the thermal test. Using the co-simulation technology, comprehensive simulation analysis of the control system, electric field and thermal field was realized. The data state of each observation point could be directly observed at one time, including the output state information of the power amplifier, the output state information of the heater, and the thermal state information of the test unit. The virtual thermal test system has a predictive and guiding role for engineering thermal tests, and can realize thermal environment simulation beyond the existing thermal environment ground simulation capabilities, providing a basis for the development of future models.