An external ointment for treating diabetic ulcers and a preparation method thereof. The ointment is prepared according to the weight ratio of the following raw materials: black plum 25g-35g, calcined oyster 25g-35g, safflower 15g-25g, flavescens 15g-25g, pinellia 15g-25g, Kochia chinensis 15g-25g, white moss bark 15g-25g, comfrey 25g-35g, catechu 20g-30g, Qingdai 5g-15g, red dates 15g-25g, Codonopsis 10g-20g, polygonatum 10g-20g , Magnolia officinalis 10g-20g, Chinese yam 25g-35g, pearl powder 15g-25g, breviscapine 10g-20g, sycamore leaves 25g-35g, pomegranate peel 25g-35g, mugwort leaves 10g-20g, saponins 10g-20g, Poria cocos 10g -20g, Luo Han Guo 10g-20g, Prunella vulgaris 15g-25g, Sushu 15g-25g, Astragalus 30g-50g, beeswax 60-150g, vitamin C? 100-200mg, anisodamine 20-40mg. The traditional Chinese medicine preparation of the invention has scientific prescription compatibility, definite curative effect, high safety, and controllable quality; the dosage of raw materials is low, which greatly saves production costs, and provides the possibility for industrialized production and popularization among consumer groups. The ointment is effective in treating diabetic ulcers with few adverse effects.