Dicyclopentadiene-based phenolic monomer(DCPDNO) was synthesized by Friedel-Crafts reaction using dicyclopentadiene and phenol as raw material. The resulting DCPDNO was reacted with paraformaldehyde and aniline to synthesize dicyclopentadiene-based benzoxazine (DCPD-BOZ). The obtained DCPD-BOZ was mixed with epoxy resin，and then cured at high temperature. The chemical structure of the synthesized product was analyzed by FT-IR, ¹H-NMR, ¹³C-NMR and the like, and the product was proved to be the target product. The curing properties of DCPD-BOZ and DCPD-BOZ/E-51 blends were studied by DSC. the thermal stability of dicyclopentadiene-based benzoxazine poly (DCPD-BOZ) and cured DCPD-BOZ/E-51 blends was studied by TGA，with testing its dielectric property. The results show that DCPD-BOZ has a curing peak at 207 ℃. Under N₂ condition, poly (DCPD-BOZ) has the 5% mass loss temperature of 305 ℃, and has the fastest thermal decomposition rate at 390 ℃. The residual carbon rate at 800 ℃ is 35%. Its dielectric constant of room temperature is 2.96，and dissipation factor is 0.019.The DCPD-BOZ/E-51 blends show a reaction peak at 240 ℃ and the DCPD-BOZ/E-51 blends have a mass loss temperature of 357 ℃ under 5%, increased by 56 ℃.