An implicit algorithm for solving three-dimensional viscous compressible flow on unstructured grids was described.Newton's method and Roe approximate scheme which was used to evaluate the flux Jacobians were chosen to solve Navier-Stokes equations.Three representative flow cases including plate

transonic turbine vane Mark-Ⅱ and CW-22 were simulated.The results of numerical simulation show favorable agreement with exact solution in theory and experimental data

and the flow phenomena such as shock and secondary flow were predicted accurately.These suggest that this unstructured implicit Navier-Stokes flow solver can predict aerodynamic performance correctly.