A waterproof, rustproof, and anti-tangling positioning device for flagpoles, comprising a positioning lock, a core shaft, a bearing, a bearing seat and a waterproof platform, the positioning lock is detachably connected to one end of the core shaft, the bearing is sleeved on an inner side of the other end of the core shaft, the bearing seat is sleeved on an outer side of the bearing, the waterproof platform is detachably connected to one end of the core shaft away from the positioning lock, the waterproof platform is arranged on an outer side of the bearing and the bearing seat. The invention combines multiple structures such as the positioning lock, the core shaft, the bearing, the bearing seat and the waterproof platform, and has good waterproof, rustproof and anti-tangling properties; the above structure can be applied to flags of different sizes, increasing the service life and aesthetics of products.