[Objective] The paper was to study the effects of different ratios of N, P and K on yield of potato intercropped with sugarcane in Lateritic red earth area of Guangxi, and seek the best N, P and K ratio for nutrition model of potato inter- cropped with sugarcane. [Method]Two field experiments adopted the optimum com- pound design （311-A） were conducted in Long＇an County of Guangxi Province in 2011 and 2012, respectively. The polynomial regression models of fertilizer applica- tion and quadratic of three factors were established by SAS statistical analysis soft- ware, and optimum nutrient simulation models of potato were obtained by computer processing. [Result] The combined application of low nitrogen and mid-high potassi- um and phosphorus fertilizer contributed to higher potato yield in experimental condi- tion. The regression model of potato yield （Yll and Y12） and dosage of N（X1）, P （X2）, K（X3） were established by using SAS statistical analysis software, in 2011 and 2012, respectively. They were Y11 =14 725.28 -415.39X1 ＋741.99X2 ＋607.83）（3-447.92X1X2- 144.09X1X3 -405.83X2X3 -267.82X1^2-795.67X2^2 -642.10X3^2, R =0.927 2; and Y12 =14 342.60 -896.25X1 ＋548.62X2 ＋925.51 X3 ＋67.81 X1X2 ＋531.60X1X3 -99.00X2X3 -904.00X1^2 - 1121.36X2^2-596.64X3^2,R=0.926 6. The regression mathematics model of potato yields preferably fit with actual situation in the locality, and have higher practical value, so it could be used for fertilizer decision and forecast. Using the computer to carry on the optimization, the N, P and K dosage of the best potato yield intercropped with sugarcane was obtained. The dosage of N, P2O5, K2O were 108.8-140.6, 172.5-204.4 and 285.9 kg/hm2, respectively. [Conclusion] The best N, P and K ratio of potato yield intercropped with sugarcane was 1：（1.23-1.68）：（2.03-2.63）.
