Underwater heavy-load telescopic supporting leg

The utility model relates to the technical field of underwater robots, and particularly discloses an underwater heavy-load telescopic supporting leg which comprises a bottom plate, a cylinder barrel, an electric telescopic cylinder, a cover plate, a connecting sleeve, a supporting block, a cylinder sleeve and a piston rod. A connector used for wiring to achieve connection between the electric telescopic cylinder and an external console is arranged on the side portion of the cylinder barrel, a first connecting plate detachably, hermetically and fixedly connected with the cover plate is arranged at the upper end of the cylinder barrel, the upper end of the connecting sleeve is fixedly connected with the supporting block, and a knuckle bearing is arranged at the lower end of the connecting sleeve. The cylinder sleeve penetrates through the cover plate and the first connecting plate and is fixedly arranged on the cover plate in a sealed mode, a sealing piece is arranged in the cylinder sleeve, the lower end of th