Cyclization reaction product synthesized by the end-to-end ring closure reaction of a telechelic polystyrene with molecular weight of 38K in extremely dilute conditions was carefully characterized by using two kinds of HPLC techniques, that is, liquid chromatography at the critical condition (LCCC) and size exclusion chromatography (SEC). First, the cyclization reaction product was coarsely separated into linear species and cyclic ones by LCCC; second, each fraction was further separated by high-resolution SEC. It was found from the HPLC analyses that the cyclization reaction product contains both linear and cyclic condensation products. Furthermore, dimeric, trimeric, and more multimeric cyclic molecules with reasonable abundance were identified as well as the monomeric cyclic molecule with high yield, as much as 50%, in the cyclic products.