Abstract: A combined model is established for simulating photosynthesis of summer maize based on the data observed with Li-6200. Validation of the canopy photosynthesis model by the data observed with GHX-305 CO₂ Analyzer is conducted. The result shows that the mean error of the model is about 6.93%. The impact of temperature on summer maize photosynthetic productivity is derived by the model, which provides the premise for improving numerical models of climatically productive potential of summer maize in the Huanghuaihai Region.