The invention discloses a compound bactericide for controlling tomato gray mold and belongs to the field of research and development of biological pesticide preparations. The compound bactericide is prepared from tetramycin and fluazinam, and is prepared according to the mass ratio of tetramycin to fluazinam at 7:1 to 1:7, preferably at 3:1. According to the compound bactericide, chemical reactiondoes not occur between the two basic materials, and the compound bactericide has an obvious synergistic effect or additive effect and is safe to use. The compound bactericide has very good poisoningactivity for different types of gray mold in fields at present, is apparently higher in effect than single dosage of tetramycin or fluazinam, and is suitable for controlling omato gray mold in vast rural areas.