The "3414" experiment design was employed to investigate the effects of N, P and K combination on yield of spring maize Zhengdan 958, and analyze the benefits. The results showed that the N, P and K combinationsimproved yield effectively, and the top three treatments were N₃P₂K₂, N₂P₃K₂ and N₂P₂K₂treatment. The yields were 15 347.0 kg/hm², 15 038.0 kg/hm² and 14 935.0 kg/hm², respectively. The yield-increasing effect of N, P and K fer-tilizer was followed as N＞P＞K fertilizer. Three treatments of the most benefits were N₂P₂K₂, N₂P₂K₁ and N₂P₃K₂,with 27 012.51 yuan/hm², 26 983.37yuan/hm² and 26 070.25 yuan/hm², respectively. In theory, the N₂P₂K₂treatment（N:260 kg/hm², P₂O₅:130 kg/hm², K₂O:130 kg/hm²） was appropriate fertilizer combination in the experimentalfields with the highest benefits and better yield. Calculating the derivative of ternary quadratic fertilizer responseequation, the results indicated that the maximum amount of fertilizer of pure N, P₂O₅ and K₂O were 361.61 kg/hm²,185.26 kg/hm² and 133.09 kg/hm², respectively. Analyzing this ternary quadratic fertilizer response equation, the re-sults showed that the practical and optimal amount of fertilizer of pure N, P₂O₅ and K₂O were 290.15 kg/hm², 149.62kg/hm² and 100.15 kg/hm². This analytic result can be recommended as the optimal amount of fertilizer on local spring maize, because the practical and optimal amount of fertilizer was not only close to theoretical and optimal amount, but also lower than the maximum amount of fertilizer.