Abstract: Tobacco target spot is a tobacco disease caused by Thanatephorus cucumeris(Frank) Donk.The laboratory test showed that 6% Mitaijunjing aqueous solutions(AS) had strong antibiotic effect against Thanatephorus cucumeris(Frank) Donk,after treating with 6% Mitaijunjing AS diluted at 600,the growth of mycelium was completely inhibited,the mycelium cell was damaged,the cytoplast conglomerated,the vacuole disappeared,and the intracellular fluid osmosed.The indoor tested results indicated that the EC₅₀ values of Mitaijunjing,Triadimefon and Thiophanate-Methyl were 1.059,2.435 and 9.852 μg/mL,respectively.The field experiments showed that the relative control effect of 6% Mitaijunjing AS diluted at 600 was 85.33%,which was comparable to Thiophanate-Methyl diluted at 750,and better than Carbendazim and Triadimefon.