The invention relates to a winch. The winch has a structure of a built-in motor and a planetary speed-change mechanism, and consists of a bracket, a motor, a drum, a speed changer and a bearing, wherein the motor is arranged in an inner cavity of the drum and is connected with the speed changer through a transmission shaft; the speed changer is connected with the drum; and the motor, the drum and the speed changer are arranged and fixed on the bracket through the bearing. By the winch, an auxiliary crane which has a small structure, is convenient to operate and use, and is safe and reliable can be used on various ships; and the winch with a planetary transmission speed reduction mechanism has high work reliability and a light structure, is convenient to install and use, and is safe and reliable.