Aiming at the problem that missiles are difficult to carry out testability design due to their own characteristics, a multi-signal model for testability design of missile systems is proposed. Based on the FMECA information, the failure mode in the system is determined, and the multi-signal model is used to establish a test model of the missile system. The correlation matrix of the fault-test is obtained and the system testability index is determined. Considering the shortcomings of existing algorithms such as genetic algorithm and binary particle swarm algorithm, a hybrid discrete binary particle swarm-genetic algorithm is proposed to optimize the test, reduced 22 candidate tests to 14, greatly reducing the number of tests. Finally, the experimental results show that the proposed algorithm can meet the accuracy requirements of testability index, and effectively reduce the number of tests and test costs.