Abstract: A computational fluid dyanmics code is used to simulate the flow in a test inlet valve box of turbine.The work sets two major goals:to acquire a comprehensive understanding of the complex three-dimensional flowfields in the valve box at representative operating conditions and to find out an effective tool to optimize performance at the given operating conditions.In order to improve the convergence and precision of the calculation,the numerical algorithm employs Body-fitted Coordinate (BDC) grids,the SIMPLEST method,the standard k-ε turbulence model,wall function method and the porosity method.In the results,the calculated flow pattern in the valve box and the loss coefficients of the valves appeared are in an improved agreement with the measured data.The tested values of the total pressure diverge from the numerical results,but their trends are about the same.