A protective cultivation test in cured tobacco, which means covering the tobacco field with 40- lattice net guarding against plant louse .It showed that the TMV,CMV,PVY protective cultivation of the tobacco field covering with net was apparently lower than that of the field outside the net. Moreover,the average yield, the output value, the first- class leaf proportion and the profit of the tobacco field with net were higher than that of the field outside the net.