A pump front chamber automatic compensation device for improving closed impeller backflow is provided. The automatic compensation device is mounted on the inner wall surface of the pump body front chamber, extending from the inner wall surface of the pump body front chamber to the impeller front cover plate, stopping the flow of fluid from the impeller outlet to the pump front chamber. The automatic compensation device includes a spacer plate and a compensation feedback device. One end of the spacer plate extends into the pump front chamber, and the other end is connected to the automatic compensation assembly, through which the length of the spacer extension is automatically compensated. The pump front chamber automatic compensation device can prevent the fluid flowing out of the impeller outlet from entering the front chamber of the centrifugal pump, thus improving the operating efficiency and stability of the centrifugal pump.