An out-of-plane oscillating beam nanoresonator with the ultrahigh intrinsic quality factor based on the motion transformation mechanism from torsion into rotation is reported. The nanoresonator is composed of two resonant beams which are mechanically coupled through two spring beams oscillating in an out-of-phase torsional mode. The out-of-phase torsional oscillation of the two spring beams forms a stationary point in the middle of a supporting beam, which minimizes anchor loss. The low thermoelastic damping (TED) in the nanoresonator is obtained by employing the torsional oscillation mode. The optimal study for minimizing TED has been carried out by varying the representative geometry parameters of the nanoresonator. The nanoresonator with a quality factor over 107 has been obtained by the proposed oscillation excitation method.