Abstract: The principal effects of different elliptical and compositive cut at trailing edge of a practical lobed mixer on the thermal mixing efficiency and total-pressure recovery coefficient were studied by three dimensional-computational fluid dynamics(3D-CFD) numerical simulation.The results show that the thermal mixing efficiency declines while the total-pressure recovery coefficient increases as the cut size of the elliptical sector augments.As for the models of compositive cut at trailing edge,the thermal mixing efficiency is lower than that of the original models except for the model with half sector arrangement,but the total-pressure recovery coefficient is usually higher than that of the original model.Among all the models with compositive modification,the model with half sector arrangement has the best performance.