Abstract: The inner cover of the back clamp battery used for cell phone is a type of bi-component plastic products. Its skeleton frame in the middle part is composed of ABS, and its cladding layer in the Peripheral parts consists of TPU. Two Injection molds were specially designed for the injection molding of such a product. The first one involved a side-gate mold system with fan-shaped gates and a pushing block ejecting system in the middle parts of the product. The second one has a pin-point system with two gradient pinpoint gates and also has a pushing block ejecting system and four-sides cam-pin slides. The demoulding system adopted a pushing block ejecting system. High-quality products and good economic efficiency were obtained from the two molds in practical use.