The invention relates to the technical field of ship rudder machines, and particularly provides a ship rudder machine system and a rudder steering control method thereof. The ship rudder machine system provided by the invention comprises a controller, a motor driver, a servo motor, a brake, a decelerator, a gear transmission mechanism, a rudder blade and a rudder blade position encoder, wherein an output shaft of the servo motor and the brake are coaxially arranged; the rudder blade position encoder is used for detecting the rudder angle and the rudder speed of the rudder blade in a real-time manner; the controller and the motor driver are used for accurate control; the servo motor is used for providing power through the decelerator and the gear transmission mechanism; in addition, the brake can realize quick effective braking. According to the ship rudder machine system and the rudder steering control method thereof provided by the invention, a full electric driving manner is used for replacing a conventional electrohydraulic servo driving manner, so that the precision, the simplicity and the reliability of the ship rudder machine system can be improved.