In this paper, a nanoscale dielectric capacitor was fabricated through wet transfer of CVD growth hexagonal boron nitride hBN as dielectric materials between monolayer graphene electrodes. The specific capacitance, power, and energy the capacitor with different hBN layer number were evaluated through cyclic voltammetry test. Different to traditional capacitor, whose capacitance decrease with dielectric layer distance once electrode is set, the capacitance of graphene-hBN-graphene based nanocapacitor increase with layer number before the thickness goes above 3nm at low scan rate (<50mv/s) due to the strong influence of interface quantum capacitance. The thickness-dependent stacked hBN thin film’ effective permittivity between graphene electrode was analyzed by impedance spectroscopy. we experimentally reveal that the permittivity of hBN thin film first increase then decrease with it layer number increase, which is also observed in other layered structure dielectric materials. The fabricated capacitor also shows promising transparency and flexibility.