Abstract: Three-dimensional incompressible steady time-averaged N-S equation,continuity equation and k-ε turbulence model equations are applied to calculation of the flowfield in the cascade passage with blade-angle slotted hub treatment.The mechanism of extending stability by blade-angle slotted hub treatment is elaborated by means of a three-dimensional viscous numerical simulation.It is revealed that a pressure difference between suction and pressure sides induces a strong flow which enters in the rear of the slot and pours out from the front of the slot.This flow blows off the low energe boundary layer and retards stall emergence.The SIMPLE algorithm with non-stagger grid is employed to solve the problem of the pressure oscillation.