Abstract: [Object and Method]]By developing the effect models of N fertilizer application and nitrogen from soil on photosynthesis ,the photosynthetic thetic product model of WCSODS was improved and perfected.[Result]The results were follows: The improved model could simulate wheat growth and yield formation under N stress rationally.Under deficient or sufficient N application, the correlation coefficient between leaf area is 0.9524～0.9790、0.9754～0.9865、between the dry matter above is 0.9347～0.9799、0.9108～0.9789,and between the yield is 0.8164.[Conclusion]Seen from the whole,LAI and the dry matter above’s trend were coherent under deficient or sufficient N application,which showed photosynthesis model’s modification was reasonable and parameter was exact. The new model will be most suitable to forecast wheat yield and make a decision for wheat production in Henan province.