Abstract: 
A doublelayered upward and downward insertionproof zipper, comprising a zipper base (1), an upper chain (2), a lower chain (3), and a steel tape measure (4). The upper chain (2) comprises a left upper chain (12) and a right upper chain (13). The lower chain (3) comprises a left lower chain (16) and a right lower chain (17). Left upper insertionproof plates (20) and right upper insertionproof plates (24) respectively are provided on the left upper chain (12) and the right upper chain (13). Left lower insertionproof plates (28) and right lower insertionproof plates (32) respectively are provided on the lower left chain (16) and the right lower chain (17). An upper steel tape strip (34) and a lower steel tape strip (36) are provided on the steel tape measure (4). When in use, the zipper is arranged on a piece of luggage, the left upper insertionproof plates (20) and the right upper insertionproof plates (24) respectively are utilized to close the corresponding gaps between left upper teeth (18) on the left upper chain (12) and the corresponding gaps between right upper teeth (22) on the right upper chain (13), the left lower insertionproof plates (28) and the right lower insertionproof plates (32) respectively are utilized to close the corresponding gaps between left lower teeth (26) on the left lower chain (16) and the corresponding gaps between right lower teeth (30) on the right lower chain (17), and the upper steel tape strip (34) and the lower steel tape strip (36) are utilized to close the upper chain (2) and the lower chain (3), thus increasing the difficulty for a criminal to open the zipper by inserting a sharp tool.
