The invention relates to a side by side composite fiber spinneret plate, a method of preparing a three-dimensional crimp antibacterial fiber filament, and an application of the three-dimensional crimp antibacterial fiber filament. The method comprises the steps that the side by side composite fiber spinneret plate is used; every two groups of rectangular spinneret orifices in unequal dimensions at 120 degrees form every equilateral three-blade A and B; an ingredient A and an ingredient B with different thermal shrinkage rates are selected; an antimicrobial agent ingredient C is added into the ingredient A; the ingredient A and the ingredient C are subjected to melt extrusion by two twin screws, enter a parallel composite component and the spinneret plate after metered, and are subjected to parallel composite distribution, cross air blow, low-temperature shock cooling, oiling and winding to form a winding yarn; and the winding yarn is subjected to drawing, false twisting and thermoforming to form a DTY (Draw Textured Yarn) or subjected to the drawing and thermoforming to form the DTY. A three-dimensional crimp antibacterial fiber prepared by the method is soft and elastic, has the characteristics of good breathability, wicking, quick drying, antibacterium and the like since various grooves are formed in the cross section, and is applied to the development of shell fabrics of undergarments, sports suits, socks, bedclothes and the like and medical dressings.