The invention discloses a bactericide composition containing carboxylic acid amide and phenylamide bactericides and a biocontrol bacterium, a preparation and applications, belonging to the field of plant protection and pesticide science. The bactericide composition comprises carboxylic acid amide bactericides, phenylamide bactericides and biocontrol bacterium powder, wherein the mass ratio of the carboxylic acid amide bactericides to the phenylamide bactericides to the biocontrol bacterium powder is (1-10) to (1-10) to (1-10); the viable count of the bacterium powder is not lower than 10<6>cfu/g; and the biocontrol bacterium is preferably bacillus amyloliquefaciens ZY-9-13, with collection number of CGMCC No.6162. The bactericide composition has the beneficial effects that the carboxylic acid amide bactericides have inhibiting effects on pathogenic oomycetes cell wall cellulose synthesis; the phenylamide bactericides can inhibit the activity of RNA polymerase in pathogenic bacteria; and by using the two kinds of bactericides and bacillus amyloliquefaciens cooperatively, the bactericide composition has excellent control effects on tobacco root knot nematode and tobacco black shank and is especially suitable for control of tobacco black shank in the field.