The invention provides TrxA-Defensin fusion proteins, a preparation method of the TrxA-Defensin fusion proteins, defensin proteins further prepared from the TrxA-Defensin fusion proteins and application thereof, and relates to the field of genetic engineering. The TrxA-Defensin fusion proteins are formed by Trx proteins and defensin proteins. In virtue of a protein fusion technology, the TrxA-Defensin fusion proteins are formed by fusing defensin protein genes with Trx genes, namely a kind of redox protein thioredoxin genes; so that, the defensin proteins are expressed in the form of fusion proteins. Tests have proven, the TrxA-Defensin fusion proteins disclosed by the invention are relatively high in expression level; moreover, the defensin proteins further prepared from the TrxA-Defensinfusion proteins are strong in bacterium-resisting effects and stable in bacterium-resisting activity. Thus, very good industrial application prospects are ensured. The TrxA-Defensin fusion proteins and the defensin proteins further prepared from the TrxA-Defensin fusion proteins disclosed by the invention can be widely applied for preparing drugs used for resisting bacteria and fungi.