The invention discloses a system and process for micro-power sewage treatment in a plateau environment. The system includes a tank body, wherein the tank body is arranged on a low-temperature antifreeze layer on surface of the plateau, the tank body is provided with a functional pool, and the functional pool includes an anaerobic pool, an anoxic pool, an aerobic pool, a sedimentation pool and a purification tank. The process comprises the steps: selecting a lighting environment, adopting a good lighting zone in the plateau environment as the selected zone, performing digging so as to form an installation pit under the surface of the selected plateau zone, installing a solar power supply device on the ground surface, introducing sewage from the anaerobic pool, adding matched composite nitrifying bacteria according to the characteristics of the sewage, guiding the sewage to flow through the entire system, finally discharging the sewage from the purification pool, and heating the sewage inside the tank body through a heating element so as to maintain the temperature at 15-25 DEG C. The invention aims to solve the problems of inconvenient sewage treatment, high cost, high energy consumption and no suitability for wide and sparsely-populated areas in the plateau environment are solved.