The invention provides a liquid carbon dioxide supplementing and supercharging device. The liquid carbon dioxide supplementing and supercharging device comprises a carbon dioxide storage tank, a reciprocating booster pump, a supercharging buffering tank, a foaming agent metering and injecting system and an extruder. The top end and the bottom end of the carbon dioxide storage tank are connected with the reciprocating booster pump through pipelines, the reciprocating booster pump is provided with a hydraulic motor and connected with the supercharging buffering tank through a pipeline, a pressure sensor is arranged at the top end of the supercharging buffering tank, a pressure sensor and a safety valve are arranged on the two sides of the pressure sensor respectively, a heating device is arranged at the bottom end in the supercharging buffering tank, a weighing sensor is arranged in the center of the top end outside the supercharging buffering tank, the supercharging buffering tank is connected with the foaming agent metering and injecting system through a pipeline, the foaming agent metering and injecting system is connected with the extruder through a pipeline, and stop valves are arranged on all the pipelines. The liquid carbon dioxide supplementing and supercharging device has the advantages that the system is stable, and cost is low.