In order to promote the photo-efficiency of traditional thioxanthone photo-initiators, 2-[2-hydroxy-3-(2-hydroxyethyl-2-methyl)amino]propoxy-thioxanthone(APTX) containing coinitiator amine was synthesized by using the ring-opening reaction of epoxy group. FT-IR and 1H-NMR analyses confirmed the structures of APTX. UV-Vis spectra showed that the maximal absorption wavelength of thioxanthone moieties became red-shift as the existence of substituents. The photo-polymerization of trimethylolpropane triacrylate (TMPTA) was made by use of photo differential scanning calorimetry (photo-DSC). The results show that APTX can effectively initiate the photo-polymerization of TMPTA.Cited