The present invention discloses an allicin-containing prevention and treatment pesticide for crop plant diseases. The pesticide can be prepared into powder, an emulsion, a microemulsion, an aqueous emulsion or a suspension by adopting allicin and a bactericidal agent as effective active ingredients, wherein a weight percentage of the allicin is 10-70% and a weight percentage of the bactericidal agent is 1-40%. The pesticide of the present invention has the following advantages that: the pesticide is prepared by compound combination of the allicin and the bactericidal agent, such that a significant synergy effect can be generated, bacterial killing and disease prevention capacity can be enhanced, bacterial killing spectrum can be enlarged, crop yields can be improved, and especially good prevention and treatment effects for gray mold, downy mildew, leaf mold, epidemic disease, and other diseases can be provided; the pesticide of the present invention provides strong affinity for crops, can be rapidly absorbed by crops, and has characteristics of pathogenic bacteria killing, plant disease inhibiting, and no residue, in addition, drug resistance is not easily generated; the use amount of the single component in the pesticide of the present invention is reduced, such that the safety on crops is improved, and the use cost is relatively low; and allicin is adopted for plant protection so as to increase selectivity of pesticide use and prompt development of plant protection technology.