Abstract: The harmonic distortion caused by the geometric nonlinearity of loudspeaker shells is investigated. The second-order and third-order harmonic vibration patterns are determined by the method of multiple scales and the finite element method. It is shown that the harmonic distortion is caused by the primary resonance and superharmonic resonance of the break-up modes of loudspeaker shells. The influences of material and geometry parameters of loudspeaker shell on the harmonic distortions are studied. Shell materials with high damping, high strength and low density can lower the harmonic distortions. The thickness of the shell has little effects on the harmonic crest values. The third-order harmonic distortion increases evidently for a conical shell with an overlarge semiapex angle.