The invention discloses a bactericide which comprises 2-methyl-methyl propionate, 2-methyl propioric acid, 1-vinyl-1-methyl-2,4-di(1-methyl vinyl)-cyclohexane, carypohyllene, 2, 6-dimethyl-6-(4-methyl-3-pentene)bicyclo[3.1.1]heptyl-2-alkenyl, 1,2,3,4,5,6,7,8-octahydro-1,4-dimethyl-7-(1-methyl ethylidene)azulene, 1,2,3,4,4a,5,6,8a-octahydro-4a, 8-dimethyl-2-(1-methyl ethyl)naphthaline, 3,3,7,11-tetramethyl tricyclo[6.3.0.0(2,4)]undecarbon-8-alkene and the like. The bactericide can be used for inhibiting or killing pathogenic microorganisms in the crop production process, mildew microorganisms of building materials and pathogenic microorganisms in human or animal living environments.