By analyzing the radiation impact mechanism in space ennironment, the irradiated performance degradation and the annealing effect during radiation are achieved. On the basis, accelerated life testing model under radiation stress is established, the expressions of failure time, accelerate factor, cumulative distribution function, probability density function and mean time to failure are obtained. Degradation datas under the stresses of 100, 50 and 10 Gy/s are simulated, and parameters in the accelerated life testing model are estimated. The failure time under normal radiation stress (0.03 Gy/s) is 43862 h. Basing on Weibull distribution and the simulated data under the stress of 50 Gy/s, both cumulative distribution function and mean time to failure of laser diodes are calculated, the mean time to failure is about 39755.8 h.