High speed centrifugalcompressors are widely usedinindustry.Itisimportantto understanditsinternal flow fieldin orderto design higher efficiency and pressure ratio impellers.In this paper,a 3 Dviscous code to solve the simplified Reynolds averaged Navier Stokes equations has been developed. The viscous effect is simulated by viscous bodyforce method.The governing equations are spatially discretizedinthe cell vortex finite volume scheme on a simple Hmesh.Theturbulence closureis made usingthe Baldwin Lomax model.This codeis demonstratedfor predictingtheinternalflow field of a high speed impeller.Some laser measured results are also illustratedfor comparing with calculated data.