Abstract: The conductive composite synthetic fibers which prepared by polypyrrloe depositing polymerization, It’s uniformity of conductive coating and adhesion stress between coating and fibrous matrix are poor. This research attempted to prepare PPy/PET conductive fibers by alkali-treatment and pyrrole liquid-phase deposition polymerization, the uniformity of coatings and adhesion stress were investigated by SEM and abrasion testing, it was found that the alkali-treatment can improve uniformity and adhesion stress of coatings, and the electrical capability was improved . PET fibers’ structure and performance which effected by alkali-treatment were investigated by a series of thermal analysis, such as DSC,DMA,TG, the experimental results showed that degree of fibers’ crystal decreased and Tg increased after the alkali treatment; PPy/PET fibers has better heat resistance due to the PPy coatings. At the same time, this research also optimized processing conditions of alkali-treatment to PET fibers.