Abstract: In order to search for the optimum drying method of porcine serum immunoglobulin G(IgG), the feasibility of spray drying and practical effects of thermal protectants were investigated in this paper. The effects of drying methods on porcine serum IgG activity and purity were compared. The results showed that the activity loss of porcine serum IgG was reduced effectively by combining with protectants which was made up of 0.5% (m/V) glycine, 5% (m/V) maltase and 20%(m/V) defatted milk powder during spray drying. The activity loss of porcine serum IgG was reduced using mycoses as the protectants. The content and activity preservation rate of IgG depend on the drying methods and drying protectants.