Abstract: Three dimensional N S equation is discretized by a finite difference scheme with three order TVD property.Arbitrarily curved surface generation technique and multi block method are employed to simulate the film cooling flow field in a turbine cascade with arbitrary numbers of coolant holes.The development of counter rotating vortices in coolant mixing flow field is expounded,including its origination,disappearing and the distribution of temperature near coolant trajectory.The result shows that the solver with domains arbitrarily decomposed developed in this paper can simulate the flow field well,and the description of coolant jet flow field in the turbine cascade is reasonable.