Abstract: A teeth-whitening strip includes a soft film layer, a backing layer, and a gel layer positioned therebetween. The gel layer includes the following components by weight: 0.50-30.0 parts of an acrylate copolymer gelling agent for excellent marginal sealing effect, 10.0-50.0 parts of deionized water, 0.10-15.0 parts of a whitening agent, 0.010-2.0 parts of a pH regulator, 0.010-0.30 parts of a sweetener, 0.010-5.0 parts of a desensitizer, 0.0010-0.10 parts of a stabilizer, and 0.050-1.50 parts of a flavoring agent. Its preparation method includes: mixing the above components to obtain a mixture; homogenizing and emulsifying the mixture to obtain a gel; coating the gel on a PET backing film to obtain a paste; baking the paste in an oven; and embossing a PE soft film on a surface of the paste to obtain the gum-protecting and teeth-whitening strip.