The invention provides a film bulk acoustic wave resonator prepared by employing ultrathin piezoelectric single crystals. The resonator comprises a high-resistance substrate with a ground chamber, and a sandwich active structure formed by clamping piezoelectrics through an upper metal electrode and a lower metal electrode. The sandwich active structure is arranged at the upper end of the high-resistance substrate. The piezoelectrics are ultrathin piezoelectric single crystals. A plurality of support posts are arranged in the ground chamber. The piezoelectric single crystals applied to the ultrathin piezoelectric single crystals are all practical piezoelectric single crystals, such as quartz, lithium tantalite, lithium tetraborate, bismuth germanate, bismuth silicate, lanthanum gallium silicate series, aluminium orthophosphate and potassium niobate. The high-resistance substrate is made of general substrate materials such as silicon, quartz, silicon carbide, aluminium oxide, sapphire and diamond in the microelectronic technology. The resonator has the advantages that the crystal completeness of the ultrathin piezoelectric single crystals is not damaged, and the ultrathin piezoelectric single crystals are perfect single crystals; the crystals and crystal orientation can be freely selected, and therefore the performance of the device is optimized; and the prospect of the production technology of the ultrathin piezoelectric single crystals is bright.