The use of polyhexamethylene guanidine hydrochloride as preservative for preventing and controlling citrus sour rot and its application are disclosed by the present invention. The citrus preservative calculated by 100% total mass fraction comprises 0.05%-0.5% polyhexamethylene guanidine hydrochloride, 0.05%-0.2% of one or more selected from the group consisting of a mixture of several of the following: 0.05%-0.2% imidazole fungicidebactericide, benzimidazole fungicidebactericide, pyrimethanil, fludioxonil and azoxystrobin, and 0.02%-0.15% polyethenoxy ether emulsion or quaternary ammonium salt emulsion, and the rest is water. The citrus preservative can significantly inhibit the decay of citrus fruit such as Citrus microcarpa during storage, especially the incidence of sour rot. So the commercial value of citrus is obviously increased.
