Underground storage organs enable geophytes to occupy habitat resources, to store nutrients, and thereby improve population fitness. The diversity of underground storage organs and their biomass allocation strategies have important impacts on the species composition and ecosystem function of geophytes. However, previous studies have mostly focused on geophytes in grassland ecosystems and the understanding of geophytes in forest is still lack. In this study, 693 herbaceous plant individuals were collected from altitudinal gradients in Gutianshan National Nature Reserve, Zhejiang Province, China. The types and diversity of geophytes and their underground storage organs were categorized and the absolute and relative biomass of each aboveground organ and belowground organ between geophytes and non-geophytes were compared. The results showed that:(1) the relative richness of geophytes was 69.1% and the relative abundance was 88.2%. Most were rhizomatous plants, mainly composed of Gramineae, Cyperaceae, Violaceae and ferns. (2) Except for stems, the absolute biomass of all organs of geophytes (leaves:1.94g, roots:0.65g, above:2.0g, below:4.1g) was greater than that of non-geophytes (leaves:0.26g, roots:0.13g, above:0.68g, below:0.13g). (3) The relative biomass of leaves (0.40) and stems (0.14) of geophytes was less than that of non-geophytes (leaves:0.48, stems:0.35) and the relative biomass of belowground parts of geophytes (0.56) was greater than that of non-geophytes (0.17). It found that geophytes which were mainly rhizomatous plants were the main constituents of herbaceous plants in the subtropical forest ecosystem of the Gutianshan Reserve, and were generally larger in biomass and tended to invest their biomass in belowground organs. These results provide a scientific basis for understanding the ecological strategies and functions of geophytes and the management of herbaceous communities in subtropical forests.