The bellmouth flow meter is an important component of the CP-01 compressor test platform, used for accurately measuring the intake mass flow rate of the test compressor. The compressor test facility equipped with four flowmeters of different diameters.（The diameters of the throat section are DN510、DN780、DN1050 and DN1300 respectively.），the mass flow rate measurement range covers from 17 ~ 250 kg/s. The flowmeters have the accurate appearance, high accuracy of size and form, and the good rough degree in flow surface. The mass flow rate of these flowmeters have being strict calibration, the measured flow uncertainty≤1% within the range of Mach numbers from 0.2 to 0.6, exceeding the requirements of the HB7115-2020.