Based on the wave equation of longitudinal vibration in slender pole, the formulas of frequency equations and magnitude coefficients for setting composite horn with hyperbolic transition are deduced. And according to the frequency equations, the influence of ultrasonic tools on the resonance performance of composite horn is discussed. With the increase of the length and the diameter of tools, the resonance frequency of horn decreases. In order to keep good resonance, the end length of horn should be adjuste...