The invention discloses a bearing water-proof mechanism of a water-cooling single screw compressor, comprising a bracket shaft, a bearing, a bearing seat, a sealed inner ring and a sealed outer ring, wherein, the sealed inner ring and the inner wall of the bearing seat form a primary radial maze sealing structure, and the sealed outer ring and the sealed inner ring form a secondary radial maze sealing structure; the upper part of an upper end head on the sealed outer ring extends into the cover slot of the sealed inner ring; the outer wall body of the cover slot, the cover slot and the upper end head on the sealed outer ring form an axial maze sealing structure; the outer wall body of the cover slot, the outer wall of the upper end part of the sealed outer ring and the inner wall of the bearing seat surround to from a ponding slot, and the bearing seat is provided with a drainage path communicated with the ponding slot; the inner wall of the bearing wall is provided with a water retaining cushion whose inner ring is provided with an airtight ring slot; the inner ring of the water retaining cushion and the outer wall of the lower end part of the sealed inner ring form a third-levelradial maze sealing structure, and the water retaining cushion is provide with a water collecting tank and a water discharging tank for discharging water. The invention has the advantages of favourable sealing and anti-leakage effect and favourable assembly and disassembly performance and is favourable for ensuring the service life of the bearing and improving the service reliability of the product.