4-benzoyl-4-methoxyldiphenylethylene, 4-benzoyl-3,4-dimethoxyldiphenylethylene, and 4-benzoyl-3,4,5-Trimethoxyldiphenylethylene are studied as near-ultraviolet photoinitiators. Light trigger property is studied systematically via illumination experiment and Photo-DSC, and the influence of photoinitiativity is studied by different amount of methoxyl groups, illumination time and concentration of photoinitiator. The results show that the monomer polymerization rate of three compounds measured by the Photo-DSC are 0.065 32 s -1, 0.102 01 s -1 and 0.163 23 s -1. Thus photoinitiation of photoinitiators can be effectively increased by increasing the number of attached methoxy groups. The ratio of photopolymerization yield between two photoinitiators gradually decreases with the increase of illumination time or concentration of photoinitiator, and it tends to be stable.