Cutting-off the trailing edge on the guide vanes increase the exhaust area of low pressure turbine (LPT) guider. It’s a convenient method to increase flow capacity of LPT. Numerical simulation was used to study effects of cutting-off trailing edge on aerodynamic performance of LPT cascade. The aerodynamic performance variation of cutting-off trailing edge for 2.5%,5% and 7.5% chord was displayed. And three different modifying shape methods were used after cutting-off trailing edge. Result shows: Cutting-off trailing edge can increase flow capacity of the passage in cascade. Flow capacity and flow loss are positively associated with the length of cutting-off trailing edge. Methods of modifying shape can affect loss of the cascade. Modifying the shape of profile tail to ellipse has most effect on decreasing cutting loss. It can reduce end-wall loss and wake loss at same time. Cutting-off trailing edge has a weak influence on the exhaust flow angle of cascade. Different modifying shape methods cause the positive variations of cascade exhaust flow angle form 0.13° to 0.16° while cutting-off length increase for 1% chord.