The short absorption wavelengths of common selenium salt photoinitiatorsmake them challenging to match with LED light. In this paper，coumarin-based selenium salts with different substituents were designed and synthesized based on the coumarin skeleton，and then the structure-activity relationship were systematically investigated. The UV absorptioncharacteristics，photolysis behavior，and photoacid process of the synthesized photoinitiators were explored by UV-visible（UV-Vis） spectrophotometer. The kinetics of photopolymeri-zation were investigated and analyzed by Fourier transform infrared（FT-IR）. In addition，real-time nuclear magnetic resonance spectroscopy（¹H NMR） was employed to dynamicallymonitor and analyze the light action mechanism of the target compound. The results showedthat coumarin-based selenium salt was a monocomponent photoinitiator responsive to UV-visible light，which could initiate the polymerization of acrylic acid monomer，epoxy monomer and hybrid system of acrylic acid and epoxy，respectively. During hybrid polymerization process，the double bond and epoxy group conversion rate were 75%-85% and 45%-55%， respectively. This study provides a new idea for the design of long-wavelength efficient oniumsalt photoinitiators.