Application of the high impedance surface EBG structures for cylindrical conformal microstrip antenna is studied. Through modeling and numerical simulation, the effects of EBG structures on antenna resonance frequency and pattern as well as effect of curvature on antenna performance with EBG structures are obtained. The results demonstrate that the resonance frequency of antenna shifts higher frequency, the antenna pattern is improved obviously, the forward gain increases, the back lobe decrease,3 dB beam width gets narrower. The comparison research shows that the effect of curvature on cylindrical conformal microstrip antenna gain is decreased remarkably after EBG structures are applied to antenna.