The invention provides a bactericide compound for preventing and treating candidatus liberibacter and a preparation method thereof. The bactericide compound is a compound composition prepared from antibiotics, ammonium nitrate, monopotassium phosphate, magnesium sulfate, EDDHA-Fr, EDTA-Mn, EDTA-Zn, EDTA-Cu, EDTA-Co, EDTA-Ca, borax, sodium molybdate, trehalose, potassium fulvic acid, a stabilizing agent, an antifreezing agent, novel permeation promoter, a dispersing agent, an emulsifying agent and co-solvent, the pH value is regulated to 6.5, and 1000-2000ml of water is added. The composition is reasonably mixed by bactericide and multiple nutritional substances according to objective requirement of prevention and control of candidatus liberibacter, is applied by adopting a trunk transfusion method to complement advantages, has the characteristics of high efficiency, low toxicity, safety and multiple functions, and can be used for better preventing and controlling candidatus liberibacter.