The invention discloses an unmanned ship automatic berthing system and method. The system is provided with a GPS transceiving device, a wireless communication device, an electronic compass, a gyroscope, a gray scale camera, a camera, a controller, a first ultrasonic sensor and a power unit on a ship body. A positioning board of a recovery platform is provided with a black identification strip and a gray identification strip, and the recovery platform is also provided with a recovery platform pedestal, a rear support rod, a front support rod, a motor, a guide rail, a cable, an air bag, a second ultrasonic sensor and a third ultrasonic sensor, a first infrared transceiving device and a second transceiving device, and a pressure sensor. The method provided by the invention adopts a gray scale camera to judge the relative position of an unmanned ship and the positioning board above the recovery platform, thereby adjusting the course of the unmanned ship to realize accurate berthing; and a collision protection module of the recovery platform judges whether a dangerous situation such as a collision of the unmanned ship will occur according to infrared rays and ultrasonic waves, and decides whether to open the air bag to protect the unmanned ship accordingly.