The part of fertilizer effect of atypical equation recommended by agricultural experiments and statistical analysis software, Yangzhou analyzer (2.2), regression analysis of Excel fertilization appears abnormal low, even negative, from the local production of practical problems. The study adopted the principle and method of basic knowledge and the frequency of using probability theory and carried out statistical analysis on the rape field fertilizer experiment data by frequency analysis method, the optimal fertilization rape yield was 1732.4 kg/hm², nitrogen, phosphorus, potassium optimization combination ranges were 210.36- 149.64 kg/hm², 81.89-58.11 kg/hm², 81.89-58.11 kg/hm², coincided with testing (Tian) and local production reality. This research is based on frequency analysis, using the weighted average method with production factors to determine the different target yield, and took the high yield, stable frequency of high yield and optimizing of production measures as the combination of fertilizer saving to increase the advantage of fertilization decision-making, therefore reduce or avoid the risk of low probability. The results of this study could solve the problem of abnormal values caused by Yangzhou analyzer (2.2), regression analysis of Excel, and DPS statistical analysis software. The function of fertilizer effect equation by the analysis of variance test was not significant, and the application of the research methods of fertilization and the recommended optimization of fertilization of nitrogen, phosphorus, potassium still need to practice in further study.