The invention discloses a dephosphorization method of converter oxygen tapping. The method is characterized in that after converter smelting is finished, oxygen tapping is carried out, in the tapping process, lime, fluorite and a modifier are added, and after tapping is finished, steel ladle dephosphorization is carried out through stirring. On the premise that the technology path is not changed, the dephosphorization capacity of steel ladle slag is utilized fully, the dephosphorization efficiency of a production line is improved by 2% to 4%, the dephosphorization effect of the converter-RH technology is stably improved, the converter dephosphorization pressure is reduced, the component judgment drop caused by phosphorus content standard exceeding of a steel ladle is avoided, the cost is low, and the efficiency is high.