Construction of multicyclic polymers has emerged as an attractive challenge in the frontier of synthetic polymer chemistry. In this work, we study UV light modulated transformation of different cyclic structures based on the reversible photoaddition reactions of cinnamate groups. Monocyclic, dicyclic, and polycyclic polymer structures can be facilely transformed, by programmed photochemical regulation based on a cyclic scaffold containing two photochemical cycloaddition groups. Polycyclic polymers with dozens of macrocyclic repeating units were synthesized by the bulk polymerization of a monocyclic polymer containing two cinnamate groups.