Photoresponsive polymers have gained more and more attention in recent years since light stimulation can be spatiotemporally localized and controlled. In general, photoresponsive polymer structures are classified into two categories: one is for polymers in which the chromophores are positioned in the side-chain as pendants; while the other one covers polymers whose photoresponsive species are catenated onto the chain backbone. Since there are a number of reviews dealing with the first category, we turn our sight to focus on the main-chain photodegradable polymers, highlighting the recent progress and the rapidly expanding spectrum of well-defined light-sensitive architectures. On the basis of the variety of synthetic strategies for incorporating the photosensitive functionalities into the polymer chain, one could rationally design and construct main-chain photodegradable polymers with diverse macromolecular structures and functions. Finally, we suggest the possible future directions and perspective in this area.