Abstract: The boundary layer flow pattern on the blade surface of a two dimensional cascade is simulated numerically to investigate the transition process from laminar to turbulent flow and the length scale of transition region under different inlet Mach number and incidence.The influence mechanism of some inlet flow conditions on the transition is also elaborated.The results indicate that the inlet Mach number and incidence have significant effects on the starting and ending positions of the viscous flow transition.Under an enhanced inlet Mach number,the starting position of the transition moves forward so that the transition region becomes small.As the inlet incidence decreases,the transition region becomes smaller.