The fluid flow mathematic models in converter combined blown are set up.It is simulated for flow state and velocity distribution of gas and stir action in different behaviours of bottom blown,top blown and combined blown by software PHOENICS(Parabolic Hyperbolic or Elliptic Numerical Integration Codes Series).In normal operation condition of ejection guns,the fluid flow in bath is axisymmetric three-dimensions flow.The results reveal out dynamic main area and slowness cyclone zones,also asked dead zone abating or erasing in practice.These shows that bottom blown gun ought to 0.5~0.7 circumference diameter of fused bath using top-bottom combined blown process.