Based on the sugarcane fields of red soil in Guangxi Province, the character of microbial communities and effects of soil nutrients to microbial communities were studied under different fertilization treatments. The results showed that the optimized fertilization could improve soil microbial diversity for a long time and soil microbial growth was significantly suppressed under no fertilizer treatment. The content of total nitrogen, potassium and available potassium was closely related to the microbial community structure. We could appropriately increase the amount of potassium fertilization to stimulate soil microbial diversity and soil fertility. The content of total P was no significantly related to the microbial community structure. Therefore, the amount of phosphorus fertilizer should be applied appropriately in the sugarcane fields, should not be too much.