This paper proposes a new structure named Photonic Band Gap(PBG) for microstrip patch antenna. The new PBG structure is etched on the dielectric plane of a probefed microstrip patch antenna and arranged by a certain rule. The cylindrical conformal microstrip patch antenna with PBG structure was simulated by HFSS. The simulation results indicate that using the PBG structure which is arranged by a certain rule on the antenna could suppresse the propagation of the surface wave, significantly improve the cylindrical microstrip patch antenna bandwidth and gain, effectively improve the cylindrical microstrip patch antenna radiation pattern.