Gigantopithecus blacki is hypothesized to have been the largest primate species. Its fossil record is predominantly concentrated in the Early Pleistocene, followed by the Middle Pleistocene, while materials from the Early-Middle Pleistocene transition (EMPT, 1.2~0.7 Ma) remain relatively scarce, therefore limiting in-depth exploration of the Gigantopithecus evolutionary patterns against the backdrop of climatic shifts during the Middle Pleistocene Revolution. Systematic excavations at Yanli Cave 1 in Chongzuo, Guangxi, conducted between late 2023 and early 2024, yielded 13 dental specimens of G. blacki. The associated mammalian fossil assemblage has been identified as comprising 6 orders, 17 families, 27 genera, and 30 species. The Primates include G. blacki, Pongo weidenreichi, Hylobates sp., Macaca sp., Rhinopithecus sp., and Trachypithecus sp. The Rodentia include Hystrix kiangsenensis. The Carnivora include Cuon javanicus antiquus, Panthera tigris, Neofelis nebulosa, Catopuma temminckii, Viverra sp., Ursus thibetamus, Ailuropoda wulingshanensis, A. melanoleuca baconi, Arctonyx collaris, and Meles leucurus. The Perissodactyla include Rhinoceros sondaicus and Tapirus sinensis. The Artiodactyla consist of Sus peii, S. xiaozhu, Cervus unicolour, Elaphodus cephalophus, Muntiacus muntjak, M. reevesi, Capricornis sumatraensis, Megalovis guangxiensis, and Bos gaurus. The Proboscidea include Stegodon cf. S. orientalis and Elephas maximus. The mammalian assemblage associated with these giant ape fossils includes both late Early Pleistocene representative taxa such as A. wulingshanensis, as well as Middle Pleistocene forms like A. melanoleuca baconi. The faunal assemblage indicates a biostratigraphic age of EMPT. Comparative analysis of tooth dimensions with Gigantopithecus fossils from other localities reveals that some specimens (447, 418, 043, 653, and SG-2) from Yanli Cave 1 retain the relatively small-sized characteristic generally found in the early Early Pleistocene populations. However, other specimens (589, 326, and 715) approach the large dental size commonly found in the late Early Pleistocene populations and larger size ranges documented in the Middle Pleistocene populations. These findings are consistent with the biochronological assessment. Following the discoveries at Queque Cave and Zhanwang Cave (both located at Chongzuo, Guangxi), Yanli Cave 1 represents as a third potential EMPT Gigantopithecus locality, likely offering crucial evidence for understanding dental evolutionary patterns and adaptive strategies in response to EMPT climatic shifts.