The invention belongs to the technical field of food processing, and particularly relates to a producing method for expanding pork skin by gas puffing. The method comprises the following steps of: baking pork skin which is preprocessed and dried at the broiling temperature of 90 DEG C and the annealing temperature of 100 DEG C for 40 minutes, transferring the pork skin instantly, and baking at the broiling temperature and annealing temperature of 230 DEG C for 2 minutes. By the production method, active nutritional ingredients in the pork skin are retained effectively while the formation and generation of harmful substances are reduced. In addition, the pork skin expanded by the gas puffing has low fat content and is rehydrated when eaten, and conservation and cleaning of the pork skin are facilitated.