Abstract: A model of computation for three-dimensional mixing layers described by discrete vortex filaments is built. Based on this model, the three--dimensional mixing layers are computed numerically. The vortex structure, distribution of mean velocity, momentum thickness and mean square values of velocities at different times are given. The effects of shear rate, intensity of disturbance on flows are analysed. Some computed results are compared with related experimental ones, showing a good agreement. The results g...