Abstract: A useful method of enhancing the mixing for supersonicmixing layer is improving flow dynamics instability. In this paper, thethree-dimensional (3-D) compressible mixing layers with spanwise curvaturewas discussion. According to analyses of flow dynamics stability, thethree dimensional disturbances have lager rate of amplification, have betterability of blending in normal direction of mixing layer and can enhance themixing for 3-D compressible mixing layer in this compressible mixinglayers. This characteristic is also for supersonic and hypersonic mixinglayer, which is useful method of enhancing the mixing for supersonic andhypersonic mixing layer.