Abstract: The present invention relates to a method for producing a recombinant protein capable of increasing expression rate of a target protein and also improving solubility and folding of the expressed target protein using a modified protein disulfide isomerase (PDI) as a fusion partner, and an expression vector containing the modified PDI gene as a fusion partner. The method for preparing a recombinant protein using a modified PDI as a fusion partner according to the present invention may solve the problems concerning a low yield and solubility and folding that conventional fusion partners have, and be widely used for protein drug and industrial protein production.