Abstract: In order to enhance the mixing efficiency, the effects of spanwise curvature, spanwisevelocity and Mach number are studied by the method of DNS. When the spanwisevelocity is fixed, the larger the spanwise curvature, the larger growth rate of the 3-Ddisturbances will be for the 3-D compressible mixing layer with thespanwise curvature. The increase ofspanwise velocity can also enhance the ability of blending when the spanwise curvature is not zero.The spanwise vorticity produced by high frequency disturbance wave will break down and stretchin the course of evolution but this phenomenon is not found in the lowfrequency disturbance cases. With a high Machnumber, the most instable disturbance still has a large growth rate for the mixing with spanwisecurvature and velocity. Therefore, it is an effective method for enhancing the mixing.