Abstract: According to the method of fertilizer effect function, combined with the best environment and economic effect model, this paper studies the model of middle topdressing of Summer Maize in Zhengzhou area of Henan Province. Based on the NO₃^--N content in the soil layer and the target yield of maize, the experiment scheme of planting, basal fertilizer and topdressing of summer maize Zhengdan-958 was designed. The NDVI index value of maize canopy in topdressing period was measured by GreenSeeker plant canopy instrument. Combining with the best fertilization amount calculated by the linear plus platform model in the experiment, the linear and quadratic polynomial data fitting analysis was carried out. The linear topdressing model of Zhengdan-958 was established to guide the variable fertilization of different rows in the middle stage of maize, and its decisive coefficient was 0.9239.