As a new class of nanomaterials, topological insulators with the Dirac surface conducting state and insulating bulk state offer a promising platform for plasmonics with breaking through the frequency and integration limitation of traditional materials. The combination of topological insulators with atomic-layer materials will be significant for the realization of integrated plasmonic functional devices. Herein, we experimentally report the plasmon-enhanced photoluminescence (PL) emission behavior of molybdenum disulfide (MoS2) single layer integrated with an antimony telluride (Sb2Te3) topological insulator nanogap. It is found that the PL response of MoS2 on the nanogap is dependent on the polarization of incident light. The MoS2 PL intensity can be distinctly improved with plasmonic excitation on Sb2Te3 nanogap. These results will contribute to exploring plasmonic behaviors of topological insulators and their applications in enhanced light-matter interaction for nanoscale light emission and harvesting devices.