measuring, by the Coriolis mass flowmeter, a mass flow rate Q_m, a mixed density ρ_mix, and a medium temperature T in a pipe;

measuring, by a combination of sensors, a pressure at an inlet and an outlet of the Coriolis mass flowmeter;

performing, by a flow rate calculation module, a multi-physical field coupling calculation, calculating a plurality of pressures corresponding to different positions X in a measuring pipe of the Coriolis mass flowmeter, and generating a function curve between each of the different positions and a corresponding one of the plurality of pressures;

calculating, by the flow rate calculation module, an average pressure in the measuring pipe of the Coriolis mass flowmeter through the function curve;

calculating, by the flow rate calculation module, an average gas density ρ_g according to the average pressure;

calculating, by the flow rate calculation module, a mass liquid content η_m of a mixed medium according to the mixed density ρ_mix, the average gas density ρ_g and a liquid density ρ_l, specifically comprising

correcting, by the flow rate calculation module, the mass flow rate Q_m according to the mass liquid content η_m, the average pressure in the measuring pipe and the medium temperature T to obtain a total mass flow rate Q_m′; and

calculating, by the flow rate calculation module, a gas mass flow rate Q_g and a liquid mass flow rate Q_l according to the mass liquid content η_m and the total mass flow rate Q_m′.