Abstract: In the present study, a pot experiment was conducted to investigate the effects of relative soil water content on photosynthetic rate, leaf anatomy, biomass, and polysaccharide content in Bletilla striata (Thunb. ex A. Murray) Rchb. f.. Our results showed that drought stress decreased the photosynthetic rate, stomatal conductance, PSⅡ activity, and chlorophyll content, thinned the mesophyll, thickened the adaxial epidermis, and decreased the biomass and polysaccharide content of B. striata. The reduction in stomatal conductance was largely responsible for the decline in photosynthetic capacity in B. striata under drought stress. This, in turn, led to the reduction of biomass and polysaccharide content, and eventually affected the quality and yield of B. striata.