A double-layer open-end zipper and double-layer 3-in-one open-end zipper and the related fabrication method is disclosed. The double-layer open-end zipper are made by performing a coil spiral and broad-width fabric tape stitching step, a dyeing and drying set, a gapping size setting step, a splitting, folding and calibration step and a glue heating and bonding or stitching step to form a single-sided double-layer zipper chain tape, and then performing a zipper slide coupling step, a ultrasonic patch sealing and T cut hole punching step, a box with small guider and pins with groove fixation step, a zipper slide functioning checking step and a top stop fixation step to obtain the desired finished double-layer open-end zipper.