In order to obtain the lifetime index of the single-bar 808 nm high power semicondutor laser, an on-line monitoring system under ten workspaces is set up. Subsequent lifetime tests are completed. The conditions of these tests are 25 ℃,100 A, 50 ℃,100 A and 50 ℃, 115 A, respectively. According to the linear regression analysis, the method of least squares, goodness-of-fit test and other statistical knowledge, the power degradation model is obtained. Based on this degradation model the extrapolated lifetime of cm-bars at 25 ℃ is 2.86×109 shots. This lifetime extrapolative method based on the parameter degradation model has some advantages such as short experiment time and high veracity than other traditional accelerated aging test methods.