With Callicarpa dichotoma seedlings as test materials, using pot set four water moisture gradients, 95% of water holding capacity of the largest field (control), 75% (mild drought), 55% (moderate drought) and 35% (severe drought), we investgated the soil moisture affects C. dichotoma photosynthetic characteristics. The results show: (1) since the drought stress, the net photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductance (G_s) and water use efficiency (WUE) of C. dichotoma were decreased, while the intercellular CO₂ concentration (C_i) in mild and moderate gradually decline, under severe drought stress significantly increased; (2) with the intensification of drought stress, the light saturation point (LSP), maximum net photosynthetic rate (P_nmax), dark respiration rate (R_d) and apparent quantum efficiency(AQY) of C. dichotoma significantly reduced, and light compensation point (LCP) increased significantly (P<0.01); (3) with the increase of degree of stress, the maximum fluorescence (F_m), maximum photochemical efficiency (F_v/F_m) and PSⅡ quantum efficiency (Fv/F_o) of C. dichotoma were gradually reduced and the initial fluorescence (F_o) was significantly increased (P<0.01), since the drought stress energy distribution ratio parameters, φ_Po, Ψ_o, φ_Eo and DIo/RC are gradually increasing; (4) with the increase of stress, chlorophyll a, chlorophyll b, chlorophyll and chlorophyll a/b of C. dichotoma gradually decreased. The study showed that the decrease of the combined rate of C. dichotoma in the drought stress has both the stomatal factor and the nonstomatal factor. The photosynthetic rate of C. dichotoma under mild and moderate drought stress was dominated by stomatal restriction, while nonstomatal restriction was mainly due to severe drought stress.