Metering method of fluid meter

The invention discloses a metering method of a fluid meter. The metering method comprises the following steps of: using an ultrasonic transducer set for collecting downstream propagation time and upstream propagation time of ultrasonic waves in fluid in a metering pipe; subtracting the downstream propagation time from the upstream propagation time to obtain a propagation time difference; judging whether the propagation time difference meets the following conditions: the fluid flow stability distinguishing value is greater than the propagation time difference and less than or equal to the theoretical maximum value; if yes, calculating instantaneous flow according to the propagation time difference and the corrected propagation speed of the ultrasonic waves in the fluid in the metering tube, and performing compensation correction on the calculated instantaneous flow to obtain flow data; and performing optimization weighting processing on the flow data meeting the corresponding conditions to obtain optimal flow