Objective To prepare a new UV curable intumescent flame retardant coating, and investigate the influences of the phosphorus-nitrogen-containing flame retardant on the flame retardant property and expansion process of polyacrylate. Methods UV curable polyacrylate was synthesized using butyl acrylate, methyl methacrylate and glycidyl methacrylate, which were blended in different ratios with 2,2-dimethyl-1,3-propanediol glycerol-methacrylate phosphate (PGMH) and N,N’-Bis(2,4-di(acryloyloxy-ethyl)-[1,3,5]-triazin-2-yl)-hexane-1,6-diamine (BDAETH) to prepare UV curable intumescent flame retardant coatings. The influence of PGMH on the thermal degradation mechanism of UV curable polyacrylate was studied by thermal gravimetric analysis and Fourier transform infrared spectroscopy. The flame retardant properties and the expansion process of the intumescent flame retardant coatings were further monitored by limiting oxygen indexes and self-made equipment. Results The addition of phosphorus-nitrogen-containing flame retardant could greatly improve the coating to expand in the temperature range of 450 ~ 480 ℃ and the maximum unidirectional expansion degree reached 14. The expansion coating could isolate oxygen and thus improve the coating’s limiting oxygen index from 19 to 28. 5. Conclusion The addition of phosphorus-nitrogen-containing flame retardant enabled polyacrylate to expand during increasing temperature or combustion and to form expansion char to isolate oxygen. As a result, the flame retardant properties were improved.