A method for preventing tobacco black shank includes the steps that first, when tobacco seedlings are transplanted, 58 percent metalaxyl manganese zinc wettable powder and water are mixed according to the weight ratio of 1:600 and prepared into metalaxyl manganese zinc pesticide liquid in a dilution mode, the roots and the basal parts of the stems of the transplanted tobacco seedlings are dipped into the pesticide liquid till the roots and the basal parts of the stems are dipped to be wet, the pesticide liquid dipped by the root of each tobacco seedling is 2.5 ml to 5.0 ml, and the tobacco seedlings are transplanted after the roots are dipped with the pesticide liquid; after the tobacco seedlings are transplanted, 58 percent metalaxyl manganese zinc wettable powder and water are mixed according to the weight ratio of 1:800-1000 and prepared into metalaxyl manganese zinc pesticide liquid in a dilution mode to be applied to the tobacco plants, and 0.5 kg to 1.0 kg of pesticide liquid is applied to each tobacco plant. According to the method, the pesticide using amount is small, the cost is low, the method is easy to operate, labor and time are saved, the control effect is remarkable, the method is suitable for large-area popularization and application, and the popularization and application prospect is wide.