The invention discloses a motor with a brake in a rear end cap. The rear end cap is divided into a bearing chamber and a brake chamber, and a rotating shaft hole is formed between the bearing chamber and the brake chamber. The rear end portion of a rotating shaft penetrates the rotating shaft hole and is then placed in the brake chamber of the rear end cap, and space between the rotating shaft and the rotating shaft hole is sealed by a sealing ring. A bearing is arranged in the bearing chamber of the rear end cap, and an elastic component is assembled in a compressed way between the bearing and the rotating shaft hole. The brake is placed in the brake chamber of the rear end cap and installed in the rear end portion of the rotating shaft. The rear end cap is provided with an operation window in the side of the brake chamber. According to the invention, the rear end cap of the motor includes the brake, space between the brake and the bearing chamber is sealed, and influence of dust on a motor body is reduced. The operation window is reserved in the rear end cap, so that requirements for operating and adjusting the rear end of the motor are satisfied in real time in the motor using process. The structure is compact and simple, the occupation space is small, the motor weight is reduced, and the motor is light and convenient to maintain.