Polyester fibers are used in a great many textile and industrial materials, their undesirable electrical advantage bring about disadvantages. Direct polymerization of pyrrole on polyester fibers may provide useful tools for producing new conducting materials. Polyester/polypyrrole composite fiber was prepared by in situ oxidative polymerization from liquid phase pyrrole at room temperature. The result showed that deposition of pyrrole is an effective way to impart conductivity to polyester fiber. The Tg of coated polyester fiber decreased and the surface of Ppy coated polyester fiber displayed an evident granular structure. In addition, the Ppy coatings have good stability under washing and heating treatment, which demonstrate that polypyrrole has good affinity to polyester fiber.