Compounds 4, Rhizotia, Cercospora asparages saskii and 50 with bactericidal activity against corn mold. The results showed that compound 4 had obvious toxicity, and its toxicity to four kinds of fungi was 50. When R 1 is 4- chlorine, the antifungal effect of compound 4 (4b: strongly inhibiting rice sheath blight on three rice blast fungi and asparagus plants 100% 95%). The activity of compound 4 with 5- butyl in 1, 3,4-thiadiazole is higher than that of 1, 3,4-thiadiazole with 5- hexyl. Compound 4 has a better inhibitory effect on other fungi.