The invention provides a traditional Chinese medicine for treating body-resistance-weak and pathogen-strong type chronic osteomyelitis, and a preparation method thereof. The traditional Chinese medicine comprises a medicine for oral administration and a medicine for external use, wherein the medicine for oral administration comprises the following medicinal materials: radix achyranthis bidentatae, radix acanthopanacis semticosi, stellaria yunnanensis, codonopsis convolvulacea, ventilago leiocarpa benth, corallodiscus flabellatus, pyrola, sargentgloryvine stem, lovage, evening primrose, rhododendron delavayi, elderberry and rhizoma dioscoreae hypoglaucae; the medicine for external use comprises the following medicinal materials: pararuellia delavayana, cupparis spinosa, common andrographis herb, helwingia root, radix rubiae, siberian walking fern, paniculate spotflower herb, cryptolepis buchananii, fir club moss, radermachera sinica and cortex kadsurae radicis. The traditional Chinese medicine provided by the invention has the effects of combining oral administration and external use, strengthening the body resistance, eliminating pathogen, benefiting qi, nourishing blood, removing toxicity, promoting granulation, activating blood, dissolving stasis and relieving swelling and pains, has an extract curative effect for the body-resistance-weak and pathogen-strong type chronic osteomyelitis, and has slight toxic and side effects.