Karst caves are characterized by darkness, low temperature, high humidity, and oligotrophic organisms due to its relatively closed and strongly zonal environments. Up to now, 1626 species in 644 genera of fungi have been reported from caves and mines worldwide. In this study, we investigated the culturable mycobiota in karst caves in southwest China. In total, 251 samples from thirteen caves were collected and 2344 fungal strains were isolated using dilution plate method. Preliminary ITS analyses showed that these strains belonged to 610 species in 253 genera. Among these species, 88.0% belonged to Ascomycota, 8.0% Basidiomycota, 1.9% Mortierellomycota, 1.9% Mucoromycota, and 0.2% Glomeromycota. The majority of these species have been previously known from other environments, and some of them are known as mycorrhizal or pathogenic fungi. About 52.8% of these species were discovered for the first time in karst caves. Based on morphological and phylogenetic distinctions, 33 new species were identified and described in this paper. Meanwhile, one new genus of Cordycipitaceae, Gamszarea, and five new combinations are established. This work further demonstrated that Karst caves encompass a high fungal diversity, including a number of previously unknown species. Taxonomic novelties: New genus: Gamszarea Z.F. Zhang & L. Cai; Novel species: Amphichorda cavernicola, Aspergillus limoniformis, Aspergillus phialiformis, Aspergillus phialosimplex, Auxarthron chinense, Auxarthron guangxiense, Auxarthronopsis globiasca, Auxarthronopsis pedicellaris, Auxarthronopsis pulverea, Auxarthronopsis stercicola, Chrysosporium pallidum, Gamszarea humicola, Gamszarea lunata, Gamszarea microspora, Gymnoascus flavus, Jattaea reniformis, Lecanicillium magnisporum, Microascus collaris, Microascus levis, Microascus sparsimycelialis, Microascus superficialis, Microascus trigonus, Nigrospora globosa, Paracremonium apiculatum, Paracremonium ellipsoideum, Paraphaeosphaeria hydei, Pseudoscopulariopsis asperispora, Setophaeosphaeria microspora, Simplicillium album, Simplicillium humicola, Wardomycopsis dolichi, Wardomycopsis ellipsoconidiophora, Wardomycopsis fusca; New combinations: Gamszarea indonesiaca (Kurihara & Sukarno) Z.F. Zhang & L. Cai, Gamszarea kalimantanensis (Kurihara & Sukarno) Z.F. Zhang & L. Cai, Gamszarea restricta (Hubka, Kubátová, Nonaka, Čmoková & Řehulka) Z.F. Zhang & L. Cai, Gamszarea testudinea (Hubka, Kubátová, Nonaka, Čmoková & Řehulka) Z.F. Zhang & L. Cai, Gamszarea wallacei (H.C. Evans) Z.F. Zhang & L. Cai.