The invention relates to a preparation method for a recombined pig alpha-interferon and application thereof. The preparation method for the recombined pig alpha-interferon comprises the following steps: the construction of an expression carrier of the pig alpha-interferon, the inductive expression of a recombined microzyme, the fermentation process and the post extraction process. The preparation method has the advantages of low cultivation cost, high yield, easy product separation and purification, and the like. The PoIFN-alpha expressed through the zyme can be secreted into a fermentation supernatant in the mode of the active interferon without complicated post-treatment processes such as renaturation. In addition, the foreign protein content in the fermentation supernatant is low; therefore, the large-scale production can be easily carried out.