The invention provides a novel underwater propeller. The novel underwater propeller comprises a propelling assembly and a heat dissipation sealing assembly; a heat dissipation sealing assembly is arranged in the propelling assembly; the heat dissipation sealing assembly comprises a small propeller, a sealing ring, a watertight pipe connector, a motor hollow shaft, a motor rotor, a motor stator, a shell, a cover body, a cavity and a macromolecule sealing hose; and the motor stator is bonded to the inner side wall of the shell, the motor rotor is arranged in the motor stator, the motor hollow shaft is fixedly connected to the interior of the motor rotor, and the small propeller is fixedly connected to the bottom of the motor hollow shaft. According to the novel underwater propeller, internal circulation is achieved by designing the motor hollow shaft and the small propeller, the thermal environment in the motor is improved, and heat dissipation with higher efficiency is achieved; pressure compensation is achieved through the macromolecule sealing hose, a compensator is replaced, and the mechanism of the novel underwater propeller is simplified; a large propeller and a fairing are made of high polymer materials, are high in strength and resistant to corrosion, and are ingeniously matched with each other to achieve higher efficiency.