The present invention relates to the field of instrumentation and can be used in determining the volume and volumetric flow rate of a fluid by passing it through a measuring device in a continuous flow. Claimed method for determining the flow rate by a turbine flow meter, comprising measuring the angular velocity of the turbine and calculating the volumetric flow rate of the fluid, which is characterized in that the short-term stop the turbine, measure the dependence of the angular velocity of the turbine on time during the transition speed from the initial value to the nominal, calculate the dependence of the angular velocity of the turbine on time, compare the values of the measured and calculated angular velocities of the turbine, the value of the volume flow rate Q0 of the fluid and its density are found by minimizing the discrepancy between the measured and calculated angular velocities of the turbine, and the mass flow rate of the fluid Qm is found by the equation Qm = Q0*. The proposed method of determining the liquid flow rate by a turbine flowmeter provides greater accuracy, since it takes into account the value of the liquid density at the time of measurement.