The present disclosure relates to servo technology, and particularly to a method and a device for detecting rotation angle of a multi-turn servo, and a multi-turn servo. The method includes: driving a multi-turn servo to be at a zero-point position; obtaining an accurate angle and a number of rotation when the multi-turn servo is at the zero-point position; detecting a current angle of the multi-turn servo in a real-time manner; incrementing the number of rotation by one in response to a zero-point forward jump between a current angle and a previous angle; decrementing the number of rotation by one in response to a zero-point backward jump between the current angle and the previous angle; and determining a current rotation angle of the multi-turn servo in accordance with an accurate angle, a current angle, and the number of rotation stored on the storage.