Abstract: The gas jets of variable and non-variable angle four-hole oxygen lances for 50 t BOF have been numerically simulated by using Fluent software to study the effect of inclining angle of jet nozzles on oxygen jet flow field and syncretizing length of jet-flows. Results show that in distance near the outlet of jet-nozzle the each jet-flow is independent free-flow, with increasing distance from outlet of jet nozzle the each jet-flow continuously spreads out and merges each other into one jet-flow (stream) at certain distance; the syncretizing distance of jet-flows of non-variable angle jet nozzle A is 1. 3 m that is consistent with the cold water simulated test results in which at situation of lance level 1.3 m the spitting amount from furnace is maximum; the inclining angles of opposite angles jet hole of variable angle oxygen lances vary from lance B to lance I, and the jet-flows of these lances syncretize for two times led to abruptly reduce the furnace spitting amount ； compared with difference 1° of inclining angles, the variable angle oxygen lances with difference 0. 5° of inclining angles of opposite angles jet hole is more favorable to increase the syncretizing distance ； among the studied nine jet nozzle with inclining angles 10. 5° ~ 11.5°/12. 5°, the jet nozzle H with inclining angle 5° has maximum jet flow syncretizing distance, its theoretical furnace mouth spitting amount is lowest.