Abstract: Multi-factor Randomized Complete Block Design was set up to study the effects of different fertilization and plant density on the characteristics of grain filling and flag leaf photosynthesis during filling stage of high quality winter wheat “Longjian301”. Variance analysis on the two factors of fertilizer application dose and plant density was conducted. The results indicate that fertilizer amount and plant density influence wheat grain filling process. Moderate fertilization and high plant density are most favorable to wheat grain filling. Grain yield of 4 188.09 kg·hm^-2 is highest under high fertilization and plant density. The level of fertilization and plant density influences photosynthetic parameters in winter wheat, with the degree of effect varying with parameter and treatment. High plant density and medium fertilization are conducive for improved leaf photosynthetic rate. On the other hand, high plant density and fertilization are conducive for improved leaf transpiration rate, while high level of fertilization is conducive for improved leaf stomatal conductance. The interactive effect of fertilizer dose and plant density on grain filling, yield and photosynthetic characteristics is significant and positive. Determination of appropriate degree of fertilization and plant density for improved grain yield production should be based on the characteristics of the variety of cultivated winter wheat.