The structure of coolant jet from suction surface of turbine cascade was simulated with N S solver.Governing equation was discreted with third order Godunov scheme which has TVD property.The kidney shape vortex was generated gradually during the mixing process between coolant jet and main flow.The coolant jet bent to suction surface gradually due to the pressure gradient from pressure surface to suction surface.The dimension of kidney shape vortex increased while its strength decreased gradually during coolant jet development.A saddle point and horse shoe vortex were formed in the front of the hole because of the rigid body character of coolant jet near the hole.It is also testified that the kidney shape vortex disappeared in main flow instead of boundary surface under the condition of large coolant jet velocity.