Abstract: To explore the bryophyte diversity of underground forests in craters of Jingpohu Global Geopark, the typical investigation method was used, and a total of 3 622 bryophyte specimens were collected, and morphological and anatomical methods were used to identify the specimens. The results showed that, 292species（126 genera and 53 families） were recorded, 31 species（17 genera and 14 families） were liverworts, 261 species（109 genera and 39 families） were mosses. The number of bryophyte species of four craters was 192 species in Ⅳ, 126 species in Ⅰ, 113 species in Ⅲ, and 61 species in Ⅱ, respectively. The dominant families were Brachytheciaceae, Mniaceae, Pottiaceae, etc., accounting for 42.12% of the total species, and the dominant genera were Brachythecium, Entodon, Plagiomnium, etc., accounting for 18.49% of the total species, and the dominant species were Pylaisia polyantha, Pylaisiadelpha yokohamae, Entodon flavescens, respectively. There were 20 common species of bryophytes in four craters, and the unique species in the Ⅳcrater was the most（88 species）. The diversity of the ‘moderate interference hypothesis’ was supported, and the similarity of bryophytes between Jingpo Lake crater and Wudalianchi volcanos was high（20.42%）, which revealed that the terrain contributes greatly to the diversity. The alpha diversity of bryophytes in the crater Ⅰ exhibited a mid-peak pattern, which was in line with the ‘Mid-elevation bulge’ theory, priority should be given to the central elevation where the bryophytes were the most abundant. The study showed that the underground forests in Jingpohu Global Geopark craters preserved high bryophyte diversity and played an important role in the volcanic ecosystem of China, and a key protection should be given to bryophytes in this volcanic geological wonder to preserve genetic resources, and the results provided first-hand basic information and important scientific significance.