The paper deals with the method to improve the superplastic quality and variety mechanical property of Zn-Al superplastic material by adding rare-earth. It describes superplastic extrusion manufacture process of injection plastics molding. The process is a rapid, simple and convinient manufacturing die one. It can reduce cost, be produced in less time, and can strengthen the capability of developing, renewing and replacing the product for the enterprise. By using this process, we manufacture the decorative cover, bear frame injection plastics molding of “QTL-1300” tension-rod antenna etc. automobile radio antennas, and plunge into the practical production. Its social and economic is evidence. If this process is further developed to include automobile big covers, the economic effect will be enormous.