Geothermal two-phase flow metering device and measurement method in geothermal well and large diameter pipelines are disclosed herein. The method thereof is measuring the enthalpy and mass flow rate of the two-phase fluid in real-time. The device mainly includes a primary, a secondary and a multi-tapping pressure components. The primary component can be an Orifice plate or Nozzle or Venturi tube. The secondary component is a transmitters-transducers. The multi tapping pressure used are radius, flanges, and corners. The example system includes data signal of upstream pressure, downstream and the pressure difference of the multi tapping is recorded and calculated in the flow computer machine. A flow meter has good accuracy with less noise for a wide range of wells output and pipeline size range, which is very useful for the geothermal industry.