Detailed measurements of the mid-span flow field within and behind passage and static pressure distribution on airfoil surfaces were made in a plane cascade wind tunnel to investigate the characteristics of the large negative incidence separated flow in turbine cascades. The separated region was determind and the separated flow model was proposed by means of flow visualization method. By virtue of 2-D time marching method the flow fields with and without separation were calculated. Good agreement is found between the experimental results and the static pressure and other flow parameters distributions obtained.