The rotor-blade driving torque and the meter factor of tangential type turbine flowmeter are both deduced on theory. Based on computational fluid dynamics (CFD) and turbulence model, a numerical investigation of the turbulent flow field of tangential type turbine flowmeter is conducted to investigate the mechanism of the tangential type turbine flowmeter. The analysis method of the rotor-torque-balance in direction Z, which predicts the rotational speed ș of rotor precisely, is presented subsequently. The key information of the inner meter is obtained through analyzing the pressure flow field and velocity flow field. Comparing with the data of physical experiment, the maximum full-scale error of meter factor is just 7.51%. The results of comparison show that the simulation model and the analysis method of tangential type turbine flowmeter is feasible and effective.