The invention provides a bactericidal composition, which comprises an active component A and an active component B, wherein the component A is prochloraz or an agriculturally acceptable salt compound thereof, and the component B is pyrimethanil. The weight ratio of the component A to the component B is between 0.05 and 50, preferably between 0.08 and 30. The invention also provides a preparation method and application of the composition. Test results show that the bactericidal composition has obvious synergy, more important, the application rate is greatly reduced, the use cost is reduced, andfor certain diseases generating resistance to a prochloraz single agent, the bactericidal composition still has high activity. The bactericidal composition can effectively control certain special fungal diseases of crops, such as food crops, economic crops, fruits, vegetables, flowers and the like. By compounding bactericides with different action mechanisms and action modes, the bactericidal composition effectively reduces the application rate of each single agent, and has good functions in the aspects of enlarging the bactericidal spectrum, delaying the fungal resistance, improving the control effect and the like.