The invention discloses a quick positioning method for multi-spindle machining. The quick positioning method comprises the steps that positioning blocks corresponding to the number of spindles are correspondingly placed in key grooves with spacing equal to the spacing of the spindles; connecting rods perpendicular to the axes of the key grooves are placed on the key grooves; the positions of the positioning blocks are adjusted so that positioning holes of the positioning blocks coincide with positioning holes of the connecting rods; the positioning holes of the positioning blocks and the connecting rods are connected by positioning pins; the positioning blocks are fixed into the key grooves; the positioning pins and the connecting rods are removed; and a fixture is positioned and clamped on a workbench by the positioning holes in the positioning blocks and the key grooves. According to the quick positioning method for the multi-spindle machining, the multiple positioning blocks are controlled to be consistent in the X direction by the positioning pins and the connecting rods, the positioning blocks are fixed with screws correspondingly, the positioning pins and the connecting rodsare removed, and then one end of the fixture is positioned through the positioning holes in the positioning blocks, and the other end of the fixture is positioned through the key grooves; the operation is simple, and the labor intensity is low; the positioning is exact, and the positioning accuracy is high; the efficiency of part clamping is high; and the quick positioning method for the multi-spindle machining is equally suitable for the quick positioning of single-spindle machine tools.