Abstract: A cryogenic propellant rocket engine, a flowmeter calibration system and method for the cryogenic propellant rocket engine have been provided. The flowmeter calibration system for the cryogenic propellant rocket engine includes a container filling unit, a container, a supply pipeline, a weighing unit, a quick recovery container, a weighing and filling recovery unit and a recovery unit which are sequentially connected; the container filling unit is configured to connect a tank wagon with the container; and the supply pipeline includes a temperature sensor and a pressure sensor, as well as a first isolation valve, a reference flowmeter, a calibration flow adjusting manual valve, a vertical main pipe and N circumferentially and uniformly distributed horizontal pipes which are sequentially connected by a pipeline.