Waste Paper-Al-Plastic materials including Tetrapak beverage and milk boxes are used to extrude the WPC instead of normal wood fiber material in this research. As many WPC products are applied as exterior wallboard at present, the research on the durability and flame retardancy of Wood-Plastic Composites is important. In this paper, various durability influences and flame retardancy of WPC are analyzed in the laboratory conditions. Some experimental results are presented as follow: Water absorption of WPC is influenced by immersion time. After immersion of simulated acid rain solution and alkali environment, and accelerated ultraviolet radiation tests, WPC samples are observed with banding strength decrease. Nonetheless, the performances of WPC wallboard achieve the requirements of national code when it is properly provided with anticorrosion coating systems. Oxygen index of 27 indicates that WPC is inflammable material. Zinc borate (ZB) and ammonium polyphosphate (APP) are effective flame retardant for Paper-Al-Plastic WPC.