The triarylsulfonium salt photoinitiator has a sulfur atom that can be conjugated with three aromatic rings, and the positive charge is dispersed. After light excitation, it can be cleaved to produce polymerization active species, and the photoinitiator activity is high; it has good absorption at 365nm; it has the characteristics of fast curing speed, good surface drying, no yellowing, no migration, no odor, etc., and is cost-effective.