A third-party certification of domestic Subsea Multiphase Flow Meter (SMPFM) is completed by DNV in accordance with API RP 17S and other relevant international standards, covering a series of processes such as failure analysis, design review, calculation verification, test programs review, manufacturing, assembly, qualification test, etc. The third-party certification process of SMPFM and partial important qualification tests are systematically introduced, including temperature and pressure cycle test, environmental stress screening test, metering performance test, hyperbaric test, etc. The research work can be used as a reference for the development and localization of other subsea oil and gas engineering equipment.