Obtaining the light source with high uniformity and high stability is the key technology for the radiometric calibration of solar absolute radiometer. The existing light source in the laboratory cannot meet the uniformity and stability at the same time. Therefore, it was proposed to obtain a highly uniform and stable surface light source through galvanometer scanning. Firstly, the two-dimensional laser scanning mode was established, and the optical system with fast scanning galvanometer and off-axis mirror as the core was designed. Secondly, according to the galvanometer scanning system, the driver was established, the control software was developed, and three scanning paths were designed. Finally, the appropriate scanning path was selected for experimental verification and its uniformity and stability was tested. The experimental results show that the non-uniformity of the scanning spot of the galvanometer is better than ±1%, the divergence angle is less than ±0.26°, and the stability of the light source is better than 0.02%. The feasibility of the laser galvanometer scanning light source as the irradiance calibration light source of the absolute radiometer is verified, which provides key technical support and experimental basis for achieving high-precision solar irradiance calibration.