The invention relates to single-well metering of an oil well, in particular to a pried type oil-gas-separation single-well metering device and a metering method thereof. The pried type oil-gas-separation single-well metering device comprises a gas phase and liquid phase separating part, a gas phase and liquid phase controlling system part and a crude oil associated gas metering part. Oil (multiphase flow) from the oil well enters a rotational-flow divider to enable gas phase and liquid phasefluids to be respectively exhausted from the top and the bottom of a separator, gas phase and liquid phase can be fully separated, and the gas phase and the liquid phase which are separated are metered through a single-phase-flow mass flowmeter. The pried type oil-gas-separation single-well metering device achieves single-well continuous metering and queueteam continuous metering, solves the problems of discontinuity and inaccuracy of a traditional metering method, overcomes the technical blank that existing multiphase flowmeterscan't measure small flow, meets the requirement that the single-well oil-gas-water meter accuracy is +/-10%, improves anoil well produced water multiphase-flow oil mixed-phase conveying technique, solves the problem that a remote oil well can't be metered, meets the requirement of oil well development and is simple in metering method and reliable in performance.