Abstract:Study on ecological functions of the herbaceous layer in forest ecosystem conducted in the last two decades is reviewed. The concept of herbaceous layer in forest ecosystem is defined as living grasses and forbs, and tree seedlings usually lower than 40 cm. Herbaceous layer, together with litter, and ambient soil constitutes an understory sub-ecosystem. Herbaceous layer has been reported to have a lot of ecological functions, such as increasing ecosystem diversity, preventing water and soil loss, enhancing soil nutrition, amending soil structure, improving seedling growth, improving microclimate, and accelerating ecological restoration. However, there are several aspects that should be paid more attention in the study on herb layer in the low subtropical forest ecosystem, e. g. 1) ecological functions and benefits of herbaceous layer or litter; 2) the colonization and succession of herbaceous layer in understory of artificial forests; 3) mechanism of seedling renovation in the forest; 4) the eco-functions and mechanisms of herbaceous layer in agroforestry ecosystem; 5) screening for more excellent herbaceous species.