Regression analysis of test result has been carried out by adopting the fertilizer effect function to follow principle，the regression equation model about paddy rice output and the nitrogen，phosphorus，potassic fertilizer expect in damp purple grit mud field has been gained. The regression equation mode is Y=6406.46 + 23.3105N + 9.317P + 47.5099K-0.07359N2-0.01474P2-0.08069K2 + 0.1159NP-0.09016NK-0.1968PK. Under the premise according with fertilizer effect function law principle in the setting up range 0~3 about nitrogen phosphorus and potassic fertilizer expects，the gaining result as follows: when the maximal output is 11271.53 kg.hm － 2，the amounts applying fertilizer are respectively nitrogen fertilizer 167.17 kg.hm－2，phosphate fertilizers 111.45 kg.hm－2， potassic fertilizers（K2O）129.21 kg.hm － 2；when the best economic effect applies fertilizer to nitrogen fertilizer (N) expecting that 160.27 kg.hm－2，phosphate fertilizers（P2O5）111.28 kg .hm－2，potassic fertilizers (K2O) 113.47 kg .hm－ 2，the best economic effect applies fertilizer measuring output 11265.85 kg.hm－2.