Deep　eutectic　solvent　(DES)　is　used　as　both　photocatalyst　and　solvent　for　photoinduced　reversible　complexation-mediated　polymerization　(photo-RCMP),　which　enables　a　rapid　polymerization　to　produce　polymers　with　predictable　molar　mass　and　low　molar　mass　dispersity　(D).　This　work　illustrates　a　comprehensive　understanding　of　DES-accelerated　RCMP＇s　mechanism　and　kinetic　features　through　quantum　chemical　calculations　and　kinetic　modeling.　According　to　the　results,　electrons　transferring　from　hydrogen　bond　in　DES　to　iodine　atom　in　alkyl　iodide　(RI)　initiator　under　light　irradiation　lowers　the　decomposition　free　energy　of　complex　RI-DES.　This　procedure　facilitates　the　generation　of　primary　radicals,　thus　contributing　to　the　DES-accelerated　phenomenon.　In　the　meantime,　the　reaction　paths　are　identified　by　computation　as　(i)　decomposition　of　RI-DES　under　light　irradiation　generates　active　radicals　and　center　dot　I-DES　complex　and　(ii)　combination　of　two　center　dot　I-DES　releases　iodine　(I2)　and　regenerates　DES.　In　addition,　kinetic　modeling　based　on　the　method　of　moments　successfully　identifies　kinetic　features　of　polymerization　in　the　presence　and　absence　of　DES,　respectively.　Kinetic　modeling　shows　a　fast　increase　in　primary　radicals　concentration　and　rapid　build-up　of　the　photo-RCMP　activation-deactivation　equilibrium,　demonstrating　that　DES　is　a　beneficial　photocatalyst　and　solvent　to　enable　the　rapid　generation　of　primary　radicals　and　accelerate　the　completion　of　catalytic　cycle.　This　research　provides　an　in-depth　understanding　of　DES-involved　photo-RCMP　and　lays　a　theoretical　foundation　for　expanding　the　application　of　DES　to　other　polymerization　systems.