In this experiment, five fertilization levels of OPT, OPT-N, OPT-P, OPT-K and CK were set up in poor soil environment to study the differences in leaf characteristics, agronomic traits and nutrient content of grain sorghum under soil conditions with different nutrient contents.The results showed that: Compared with the lack of P and K, the growth and development of sorghum leaves were more sensitive to the lack of N. The contribution rate of the interaction of N, P and K to the increase of sorghum yield, grain weight per panicle, 1 000-grain weight and straw dry weight was higher than that of any two elements. The accumulation of K in sorghum straw and grain was higher than that of P, indicating that Sorghum needs more K.In the absence of soil nutrient conditions, N and K supplementation can improve the absorption of P by sorghum, while N and P can improve the absorption of K. Therefore, N supplementation is of great significance to sorghum production. It indicates that the influence of N deficiency on sorghum is obviously greater than that of K and P fertilizer. Reasonable ratio of N, P and K can promote the growth of sorghum, increase the yield and improve the quality.