The objectives of the study were to determine the effects of silicon on photosynthetic characteristics of maize on alluvial soil, including total chlorophyll contents, photosynthetic rate (P_n), stomatal conductance (g_s), transpiration rate (E) and intercellular CO₂ concentration (C_i) using the method of field experiment, in which there were five levels (0, 45, 90, 150 and 225 kg· ha^-1) of silicon supplying. The results showed that certain doses of silicon fertilizers can be used successfully in increasing the values of total chlorophyll contents, P_n, g_s and decreasing the values of E and C_i of maize leaves, which meant that photosynthetic efficiency of maize was significantly increased in different growth stages by proper doses of Si application on alluvial soil and the optimal dose of Si application was 150 kg· ha^-1. Our results indicated that silicon in proper amounts can be beneficial in increasing photosynthetic ability of maize, which would be helpful to the grain yield and growth of maize.