Abstract: Turbine rectangular cascades with conventional straight blades and negative curved ones at obtuse angles between their pressure surfaces and both endwalls were investigated in a low speed plane cascade wind tunnel.The measuring planes with five hole micro spherical probes were arranged as 3 before,6 in and 1 after the cascades.The experimental results show that the origination and development of horseshoe vortices and passage vortices as well as the meeting of the passage vortices in the midspan region almost dominate the whole flow field of conventional straight cascade.In comparison with those of conventional straight cascade,blade negative curving improves the flows around blade leading edges near both the endwalls,and reduces the intensities and viscous dissipation losses of leading edge vortices and passage vortices.As a result,the flux capability of the cascade increases by 3 2%,the mass flux averaged overall loss coefficient is cut down by 19 1%,at the same time the good inlet condition is provided for the rotor cascade.