Objective The distribution of farmland rodents were studied to provide theory foundation for rodent control in Guangdong province. Methods The rodent density of different environment was investigated using night trapping method. Results The density of farmland rodents was topmost in the intercrop region and the composing of rodents was different in various environment. In the regions that rice interplanted fruit tree or vegetable there was remarkable correlation between the distribution of rodents and rice growth stage. Rodent density in rice field was higher than in fruit or vegetable field in the second half period of rice growth, but it was the lowest after rice harvest. In a big sample site, due to the differences of crops, the development stage of the same crop and weeds condition, the rodent density varied from 1 to 4 folds with each other in usual, but the highest could reach 27.3 folds compared with the lowest. Conclusion The distribution of rodent was imbalance. On the circumstance that provided better foods and habitat, the rodent density was high. It was an effective method to control farmland rodents economically using rodenticide accurately known rat's primary habitat.