Abstract: In order to explore the impact of soil moisture content on photosynthesis, transpiration rate and stomatal conductance of spring maize in northeast China, and reveal the physiological mechanism of yield reduction due to drought, water stress and interval sowing field experiments were carried out in the spring of 2010 in the northeast central area，the soil moisture, photosynthesis rate (NPn), transpiration rate (Tr) and stomatal conductance (Gs) of the maize seedling were observed, and the relationship between these factors was analyzed. The results showed that, there was quadratic function relation between soil moisture and maize Seedling NPn, Tr and Gs, respectively. When 0-20 cm soil moisture was over 19.5%, maize leaf stomatal conductance was higher and photosynthesis and transpiration rate was exuberant. When the soil moisture was under 19.0%, the NPn and Tr decreased linearly with declining soil moisture content, with every 1% decrease in the soil moisture content, NPn and Tr decreased 1.6 μmol/(m2?s)and 0.5 mol/(m2?s) respectively. The relation between Tr, Gs and NPn was linear function respectively, with Gs and Gs decreased 1 mol/(m2?s) and 1 mmol/(m2?s) respectively, the NPn decreased 0.89 and 3.09 μmol/(m2?s) respectively. Under soil drought stress, the maize leaf stomata closed and transpiration rate decreased, which lead to fast degradation of photosynthetic rate, furthermore inhibited maize growth and caused yield reduction.