The invention discloses a closed-loop safety control system of a ship loader in the field of port shipment equipment. The closed-loop safety control system comprises a PLC (Programmable Logic Controller), a frequency converter driving unit, an electromotor and an encoder arranged on the electromotor, wherein the signal output end of the PLC is connected with the signal input end of the frequency converter driving unit, the signal output end of the frequency converter driving unit is connected with the electromotor, and the signal output end of the encoder is connected with the signal input end of the PLC. According to the closed-loop safety control system, the rotating speed of the electromotor can be detected by using the encoder, and thus the rotating speed stability of the electromotor can be ensured, and the operating safety of a ship loader driving system is improved. The closed-loop safety control system can be applied to the ship loader.