As a common linear structure on the surface of the Moon, lunar ridges have certain distribution regularity. The maps of lunar ridges obtained from the DEM data of LRO (Lunar Reconnaissance Orbiter) were analyzed, and the result revealed that most lunar ridges are of compressional formation mechanism as a combination of drag folds on the surface and thrust faults underneath. This phenomenon is probably influenced by the regional compressional stress oriented to the east-west, which is corresponding to the stress state of the tidal forces at low and middle latitudes of the Moon, and it can be inferred that tidal forces may be the main factor for the formation of these lunar ridges. It concluded that there is a strong correlation between tidal forces and the distribution styles of lunar ridges.