Southwestern Guizhou, China, is famous for hosting clusters of Carlin-type Au, Sb, and Hg-Tl deposits. These deposits are thought to be the products of a low-temperature hydrothermal metallogenic event. Calcite and fluorite are common and widespread gangue minerals in Au and Sb deposits, respectively. Ore-related calcite commonly coexists with stibnite, realgar, and orpiment at the periphery of high-grade orebodies in Au deposits, while ore-related fluorite is generally intergrown with stibnite in Sb deposits. In this study, ore-related calcite and fluorite samples from representative Au (Zimudang) and Sb (Dachang) deposits, respectively, were separated, and the rare earth element (REE) concentrations, Sm/Nd isotope ratios, and Sm-Nd isochron ages were analyzed. This study aims to determine the formation ages of the calcite and fluorite and to constrain the age of low-temperature metallogenic event in Southwestern Guizhou. The calcite and fluorite samples contain relatively high total concentrations of REEs (8.21-22.5 mu g/g for calcite, 21.7-36.6 mu g/g for fluorite), exhibit variable Sm/Nd ratios (0.51-1.01 for calcite, 0.35-0.49 for fluorite), and yield Sm-Nd isochron ages of 148.4 +/- 4.8 and 141 +/- 20 Ma, respectively. These ages are consistent with the age range constrained by the low-temperature thermochronology of zircon (132-160 Ma), crosscutting relationships of stratigraphy or intrusions (96-160 Ma), and previous dating results (135-150 Ma) in Southwestern Guizhou. Collectively, the ages obtained in this study add new evidence to previous geochronology studies, such that the low-temperature hydrothermal mineralization in Southwestern Guizhou can be constrained to 135-150 Ma, corresponding to the Yanshanian orogeny, which was associated with a weak extensional tectonic environment.