Abstract: The life prediction model of the aluminum alloy beam coating system for multiple units under laboratory salt spray environment is established, and the service life of the coating system under this environment is predicted. First of all, based on the experimental results under the laboratory salt spray environment, the water absorption dynamics model, wet adhesion GM (1,1) model and coating thickness mathematical model of the coating system are constructed, respectively. Then, the weights of the three failure factors in the coating failure process are calculated and corrected by using the grey correlation analysis method, and the mathematical model of the coating system failure is established based on these three factors. Through the mathematical statistical verification and comparison of the test results, the model has good reliability and can accurately predict the life of the aluminum alloy beam coating of multiple units under the laboratory salt spray environment.