Abstract: To select a suitable location for a Moon-based platform in the lunar south polar regions, the surface illumination, the Earth observation conditions and the slope are schosen as the main factors , which shows the solar energy and thermal environment on the lunar surface, the ability to obtain scientific data, and difficulty of construction. Based on the topography data and the orbit data of the Sun, the Earth and the Moon, an integrated solar illumination and Earth observation geometric model is established and applied to study seven key areas (M1 ~ M7). The lunar surface positions with the illumination rate greater than 80% and the Earth observation rate greater than 30% are taken as the primary selection area of the Moon-based platform, next, their slope conditions are analyzed and a grading evaluation is carried out. Combined with the characteristics of each primary selected area, three lunar positions with higher optimization level are finally recommended, which are located at the eastern edge of De Gerlache crater (in M1), the mountaintop where Sverdrup crater connects with Shackleton crater (in M4), and the mountaintop between the Shackleton crater and the Slater crater (in M7), and these results will provide reference for the follow-up lunar south polar exploration missions.