For exploring and proving the relationship between semiconductors lasers′ electrical derivatives and their reliability, 12 semiconductor lasers are put in series to electric accelerated aging until the devices do not work. Monitor the variation of semiconductors′ electric derivatives in the process. Then, the figure is gotten by dealing the experimental data. The experiment finds that the dip of the electric derivative curve at the threshold becomes smaller in the accelerated aging process; The characteristic parameter of junction and the intercept of the electrical derivative above the threshold at I=0 become larger in the accelerated aging process. And the variable of characteristic parameter keeps a small one early. Then, it becomes larger and keeps a large one some time. Finaly, it decreases quickly and keeps a small one. The phenomenon indicates that there are three stages of deterioration of devices: devices deteriorate slowly early, then deteriorate quickly and keep for some time, and devices deteriorate slowly again. There is a close relationship between electric derivatives and lifetime of devices and the deterioration of devices, and electric derivatives can characterize state of semiconductor lasers.