A reliability evaluation method was proposed for Light Emitting Diodes (LED) which the optical performance is declining nonmonotonicly. The accelerated degradation test was conducted in order to obtain luminous flux degradation data. A bi-exponential degradation model was used to fit the lumen maintenance degradation data. Comparing the model with exponential model in fitting effect, indicates that the bi-exponential model provides a good fit to the date. The pseudo failure lifetime was tested and analyzed by MATLAB program. The distribution type of pseudo failure life was determined by using Kolmogorov-Smirnov (K-S) test. The results showed that, the pseudo failure lifetime distribution of samples from two companys obeys Lognormal distribution and Weibull distribution, respectively. And the reliability evaluation of LED is made by the corresponding distribution parameters. It was obtained that the pseudo failure lifetime of samples from two companies is 5 328.37 h and 4 758.35 h, respectively. This method shows a certain reference value to reliability evaluation on nonmonotonic degradation law of LED.