In the strapdown inertial navigation system composed of interferometric fiber optic gyroscopes, the drift term caused by the temperature transience effect during the startup of fiber optic gyroscope is the main error source of navigation error and has become a limitation to further improve the performance of high-precision fiber optic gyroscope systems. In this paper, through theoretical analysis and modeling of the temperature transience effect during the startup process of the fiber optic gyroscope, a method for suppressing the error of the temperature transience effect of the fiber optic gyroscope based on lookup table is proposed, and the evaluation method of the error of the fiber optic gyroscope temperature transience effect is also proposed. The experimental results show that the suppression method can reduce the drift probability error of the fiber optic gyroscope from 0.02 ~0.50 (°)/h to less than 0.01 (°)/h at the environmental temperature of -40~+60 ℃, corresponding to the navigation circular probability error reducing from 1.4~35 n mile/h to less than 0.8 n mile/h, which effectively suppresses the error of the start-up temperature transience effect of the fiber optic gyro and greatly improves system performance.