In this work, thermosetting epoxy resins, which diglycidylether of bisphenol A (DGEBA) cured by N-benzylpyrazinium hexafluoroantimonate (BPH), were studied for thermal latent cure system. BPH has been synthesized by previous work and investigated the effect of concentrations of BPH in the rheological and thermal properties of an epoxy system. Fourier transform infrared spectroscopy(FT-IR) was used for the functional groups of BPH. Differential scanning calorimetry (DSC) was used for the thermal characterization of the thermal latent cured epoxy systems. The highest curing temperature is 202.5 oC in DGBEA/BPH1.0 sample. Thermogravimetric analyzer (TGA) was used for the thermal stability characterization of the thermal latent cured epoxy systems. The highest thermal stability is DGBEA/BPH1.0 sample. Therefore, we carried out that the cationic latent thermal catalyst had high thermal stability in cured epoxy systems. Keywords: Epoxy resins, Cationic latent thermal catalyst