The invention provides a porcine interferon alpha and an application thereof. The porcine interferon alpha is synthesized through selecting high-expression codon design according to the codon bias of the of a Escherichia coli prokaryotic expression system, the amino acid sequence of the porcine interferon alpha is represented by SEQ ID NO. 1, and the nucleotide sequence for encoding the porcine interferon alpha is represented by SEQ ID NO. 2. A method for preparing the porcine interferon alpha has the advantages of simplicity, low cost, easiness in industrial production, high expression level of the porcine interferon alpha, thorough denaturation in the inclusion body treatment process, and high protein renaturation rate porcine. The porcine interferon alpha prepared in the invention has high titer, can inhibit 100TCID50 vesicular stomatitis virus, has a specific activity reaching up to 10<8>, has good bioactive functions, can be used to prepare medicines for preventing and treating the swine virus infection and enhancing the immune function, and has a broad market application prospect.