Aiming at the problem of correlation among multiple degradation variables in the reliability evaluation of fiber optic gyro (FOG), a storage reliability evaluation method of fog based on Copula function is proposed. Firstly, the performance degradation data of fog is obtained by accelerated stress degradation test, and the Wiener process is used to model the performance degradation data, and their degradation model and life distribution are obtained. Then, the copula function is used to fuse the life data of each performance parameter to get the reliability index. Finally, the method is verified by combining the performance degradation data of fog. In ambient environment of 55 ℃ , the storage life of fog is 38 795 h when considering the correlation between parameters and 17 485 h and assuming the performance parameters are independent. The results show that the reliability index obtained by considering the correlation of performance parameters is more reasonable. At the same time, the method effectively solves the problem of multi parameter reliability evaluation of products, and has better practicability and popularization.