Abstract: In order to unravel the response characteristics of Cunninghamia lanceolata to different amounts of silicon from the perspective of photosynthetic physiology,a pot experiments were conducted in greenhouses in Yangkou state-owned forest farm in 2021 to investigate the effects of different amounts of silicon (Si) fertilizer (0,0.4,0.8,1.2 g·plant^-1) on the growth and photosynthetic characteristics of C.lanceolata seedlings by using 6-month-old superior clone seedlings ″Yang 061″ supplied with 30 g·plant^-1 of compound fertilizer (CF).Moreover, subordinate function value method was employed as well to comprehensive analyzed the growth and physiological indexes,thus selecting the suitable Si fertilizer level for C.lanceolata seedlings growth.The results showed that compared with the control and solely CF supplied treatment,Si application could promote the growth of seedling height and ground diameter to different degrees,and the seedling height and ground diameter reached their maximum at 0.8 g·plant^-1 Si treatment.Si application also significantly promote the accumulation of chlorophyll and photosynthetic pigments in C.lanceolata leaves,increase chlorophyll a/b value,maximum fluorescence (F_m),variable fluorescence (F_v), maximum photochemical efficiency of PSⅡ (F_v/F_m),potential photochemical efficiency of PSⅡ (F_v/F_o),actual quantum yield (QY) and net photosynthetic rate (P_n) in leaves,and all of the above indexes reached their maximum at 0.8 g·plant^-1 Si treatment.While the initial fluorescence (F_o),non-photochemical quenching (NPQ) and intercellular carbon dioxide concentration (C_i) of the silicon-applied leaves were lower than control.The subordinate function value method results showed that the membership value was the highest when the dosage of Si was 0.8 g·plant^-1,indicating that this is the most suitable Si concentration for the growth of C.lanceolata seedlings.In conclusion,compound fertilizer with 30 g·plant^-1 plus 0.8 g·plant^-1 Si fertilizer is the appropriate fertilization treatment for the growth of C.lanceolata seedlings.