The invention relates to an oilfield well flow real-time metering system and method. The oilfield well flow real-time metering method is characterized by comprising the following steps that (1) basic data are collected; (2) an efficiency-velocity ratio calculation module in a central data processing system works out the efficiency-velocity ratio based on the collected basic data through a power balance equation theoretical algorithm, and sends the efficiency-velocity ratio to a dimensionless velocity calculation module; (3) the dimensionless velocity calculation module works out the dimensionless velocity according to the obtained efficiency-velocity ratio and an inherent performance curve of an electric submersible pump, and sends the dimensionless velocity to a ground surface flow calculation module; (4) the ground surface flow calculation module works out the velocity of the electric submersible pump according to the obtained dimensionless velocity, and initial ground surface flow value is worked out according to the crude oil volume factor; and (5) a data calibration module is used for calibrating the obtained initial ground surface flow value according to the actual result of field measurement to obtain the final ground surface flow value. The oilfield well flow real-time metering system and method can be widely applied for monitoring the production conditions of oilfield wellheads.