While the upland cereals such as corn and soybean are the weak aspects of food crop pro-duction in Jiangxi Province,the area
of the fallow field which is suitable to the growth of cornintercropped with soybean is nearly 267 thousand hectare. So the poteintial productivity of up-land food crops is great. The quardratic regression rotation combination design was applied inthis experiment in which the row ratio of
intercropping(soybean/corn ),soybean density(plant/bunch)and the quantities of
nitrogen,potassium and phosphorus were chosen to be ex-perimental factors. As a result of statistics on the microcomputer,five mathematical modelswere set up which showed the relationships of five experimental factors with the total yield ,the total energy output,the yield value of the intercropping system,the corn yield and soy-bean yield respectively. Through the analysis of the yield model,it was known that:1)the row ratio of inter-cropping and the quantity of phosphor us were the most important factors influencing the totalyield of the intercropping system;(2)the mutual effect between the row ratio and soybean den-sity was a positive one which meant a high row ratio should be coupled with high soybean den-sity to get optimum yield;(3)the multual effect between the soybean density and the quantityof nitrogen was a negative one which meant the high soybean density should be coupled withlow amount of nitrogen appllcation. By stimulation of the yield model,the optimal culture prac-tices with total yield more than 4 500 kg per hectare were achieved which were a set of reliabletechnique to be applied in production.