Ion irradiation of polymers can induce irreversible changes in their macroscopic properties such as electrical and optical properties and the surface-related mechanical properties. Electronic excitation, ionization, chains scission, cross-links and mass losses are accepted as the fundamental events that give rise to the observed macroscopic changes. Detailed and systematic study of radiation induced effects in polymers enriches not only the knowledge of ion-material interactions but also supplies new bases for polymeric materials synthesis through ion-beam technologies. Previous work has concentrated mainly on effects induced by low-ionization particles such as γ-rays and electrons. Since 1980’s the application of high energy heavy ion accelerators enables the use of high energy heavy ion as an irradiation source, and many new and exciting effects and phenomena have been revealed.