The invention provides a cyclic polymer and a preparation method and application thereof. The preparation method comprises the steps that 2,5-dibromohydroquinone serving as a raw material is subjectedto a substitution reaction and Click cross-coupling to obtain 1,4-di-[2-(4-methylamino-1,2,3-triazole)-ethoxy]-2,5-dibromo-benzene; tris(4-bromophenyl)methylamine is esterified by boric acid to obtain tris[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan)phenyl]methane; 1,4-di-[2-(4-methylamino-1,2,3-triazole)-ethoxy]-2,5-dibromo-benzene and tris[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan)phenyl]methaneare subjected to a Suzuki coupling reaction, acidification de-esterification and quaternization to obtain the cyclic polymer. The polymer can be used as an antibacterial agent and has small cytotoxicity. The polymer is easy to prepare, mild in reaction and high in yield. The polymer can emit fluorescence and also be used for bioluminescent imaging.