High brightness is an important direction of development of laser. How to improve the average brightness of laser by the prevailing digital technology is discussed. Based on the analysis of the influencing factors of average brightness, eight projects for improving brightness are compared and analyzed, and the best way for digital high average brightness laser (DHABL) with the coherent beam combination of chains of master oscillator power-amplifier (MOPA) is chosen. The concept and the project of DHABL are presented.