The effect of radiation wave range on living behavior of ambient temperature reversible addition fragmentation chain transfer ( RAFT) radical polymerization mediated by either trithiocarbonates or dithioesters chain transfer agents (CTAs) was investigated using UV-vis radiation sources with various wave ranges. The results indicate that CTAs are strongly sensitive to the UV radiation with wave range around their characteristic absorption wavelength, leading to significant decomposition of CTA moieties in the duration of RAFT polymerization, undermining the living character of polymerization. Cutting off these CTA-sensitive short-wave radiations significantly improves the living behavior of these polymerizations. Addition of highly efficient photoinitiator and optimizing functional groups of CTA remarkably suppress retardation effect in RAFT process, thus significantly shortening the initialization period and accelerating overall RAFT process. These provide a facile way toward rapid and well-controlled ambient temperature RAFT polymerization.