Abstract: The second harmonic sound beam distribution nonlinearly generated by a conical source has beed derived. Theoretical results indicate that the second harmonic beam is distributed as a Bessel function along the radial direction, and independent of the propagation distance. Another important feature is that the beamwidth of the second harmonic component is just equal to 1/2 times as that of the fundamental, not as 1/\sqrt2 times in the general cases. A potential application of this sound beam in the acoustic nonlinear parameter B/A imaging or measurement is also discussed.