The invention discloses a method for preventing and controlling tobacco root-knot nematodes. The method comprises the following steps: interplanting tobaccos and crotalaria juncea; sowing and culturing seedlings 50 to 60 days before the tobaccos are interplanted, and sowing and culturing seedlings 20 to 25 days before the crotalaria juncea are interplanted; from April to May of every year, transplanting the seedlings of the tobaccos and the crotalaria juncea to carry out synchronous interplanting, wherein the plant-row distance of tobacco plants is 55-65cm and 110-120cm, and the crotalaria juncea are interplanted at the middle positions of the plant distance or the row distance of the tobacco plants. The method disclosed by the invention has the advantages that the crotalaria juncea is used for reducing the occurrence of the disease of the tobacco root-knot nematodes for the first time; the interplanting of the tobaccos and the crotalaria juncea is utilized for preventing and controlling the tobacco root-knot nematodes, so that the preventing and controlling effect is good and the quality of the tobacco leaves is improved; the operation is simple, the practicability is strong, the preventing and controlling effect of the disease of the tobacco root-knot nematodes is improved and the occurrence of the disease of the tobacco root-knot nematodes is reduced.