The reliability is the important performance of high power semiconductor laser. Thermally accelerated ageing test is an important technology of lifetime evaluation and reliability analysis. In this study, three groups of thermally accelerated ageing tests of conduction-cooled-packaged 60W 808nm high power diode laser arrays packaged by Indium solder at constant current have been carried out. Analysis of ageing data suggest the extrapolated lifetime under room temperature to value device reliability. We also analyze and discuss the degradation modes. This work can provide guidance for optimizing the chip and package structure, is helpful for improving performance and enhancing reliability of high power semiconductor lasers.