Abstract: The combination design of tip endwall contouring and positive leaned vane in low aspect ratio turbine nozzle can not only reduce secondary losses on both endwalls,but also match the requirements for using plain blade body when impingement cooling is in use.The paper describes the mechanical mechanism and the flow field character that how the combination design redues the secondary losses.A quality factor which allows qualitative evaluation of the effect of blade design on secondary losses is selected and verified.Based on a lot of 3D computations,the paper investigates in detail the effect of some main characteristic parameters on 3D flowfield,such as leaned angles,the start place of tip endwall contraction and the curvatures of the contours,etc.The design method, steps and the evaluation criteria of flowfield quality have been given.The combination design method has significance for the successful design of a low aspect ratio high temperature turbine nozzle.