With the improvement of self output power and conversion efficiency, semiconductor lasers have been widely used in laser processing field. Aiming at current requirement for hardening light source of semiconductor laser in laser processing field, a continuous output hardening light source of semiconductor laser with a wavelength of 976 mm was developed. The light source reached higher beam combination efficiency by adopting space / polarization beam combination technique, and better homogenized inherent light intensity fluctuation along slow axis for laser bar by adopting array division of cylindrical micro lens combined with focusing lens, thus making light intensity of focus spots flatly distributed. Finally, the light source was adjusted and tested experimentally. The results show that when the working current is 93 A, the maximum output power of the light source is 5 120 W, the electro-optical conversion efficiency reaches 47%, the spot size is 2 mm×16 mm and the flatness of the spot distribution is over 90%, which meet the requirement for large-scale high efficiency laser hardening in industry.