The invention relates to a fluid flow metering device, in particular to a three-differential-pressure gas liquid two-phase fluid flow metering device capable of measuring gas liquid mixed fluid. The device comprises a horizontal pipe and a vertical pipe, wherein the horizontal pipe and the vertical pipe are connected with an inlet and an outlet of an elbow sensor respectively; pressure introducing ports on the inner side and the outer side of the elbow sensor are connected to a first pressure difference transmitter; two pressure introducing ports are arranged on the vertical pipe at intervals and are connected to a second pressure difference transmitter; two pressure introducing ports are arranged on the horizontal pipe at intervals and are connected to a third pressure difference transmitter; the space between the two pressure introducing ports of the second pressure difference transmitter is equal to the space between the two pressure introducing ports of the third pressure difference transmitter; and signal output ends of the first pressure difference transmitter, the second pressure difference transmitter and the third pressure difference transmitter are connected to an integrating meter. The three-differential-pressure gas liquid two-phase fluid flow metering device has a compact structure, does not additional pressure loss, has wear resistance and high pressure resistance and is difficult to block, wherein the precision of the device can be controlled to be within 1 percent completely; a new idea is provided for solving the metering problems of gas liquid two-phase fluid; and the applicability and the precision of measuring a high-pressure high-flow-velocity medium are more excellent than those of the traditional mass flowmeter.