The Interlock sewing machine is also called a special sewing machine, and the stitches stitched by the stitching are chain stitching stitches. This stitch is mostly used for the rolling collar, piping, folding, seaming, stitching and trimming of knitted garments in recent years. The styles of ready-to-wear garments vary widely, and the Interlock sewing machine is often used in the use of quilted decorative stitches, and there are many variations in the stitching patterns of the stitching machine, such as three-needle four-line stitching (No. 407). The stitch can be changed into a two-needle three-line stretch (line 406), or a two-needle three-line stretch can be changed into a two-needle four-line stretch or a three-needle five-line stretch (602 stitch or 605 stitch) In order to better understand the use of the Interlock sewing machine, the following research will be carried out from the aspects of the conveying power of the Interlock sewing machine, the design of the handpiece, and the change of the stitches, and the use of the Interlock sewing machine will be fully utilized.