It has been proved that there are two types of corn growing soils,balanced or unbalanced in soil nutrient supply. Therefore it is necessary to recommend proper nutrient ratios to achieve high yield of corn. A field experiment was carried out on calcareous drab soil,which is balanced in nutrient supply,in Shanxi to explore maximum fertilization rate and optimal fer tilization ratio forhigh yield of corn N and P application rates were set in two ways,with fixed N/P ratio or with N rate varying with P rate Results show that in the treatment with fixed N/P ratio,the maximum N application rate was 235 4 kg hm^-2,the highest corn yield 10 213 kg hm^-2,the optimum N application rate as 207 1 kg hm^-2,its corresponding yield 10 163 kg hm^-2,46 kg hm^-2,738 kg hm^-2,39 kg hm^-2 and 723 kg hm^-2 higher respectively than in the other,showing every additional kilogram of N could bring about an additional yield of 18 5 kg. The experiment demonstrated that N/P ratio of fertilization is the most important factor affecting maximum N rate and economic benefits. Through increasing N and P application rates while keeping them at a fixed rat io an optimal fertilization rate could be obtained.