Objective In view of the problems that the ultrasonic cutter size is difficult to be calculated analytically and the ultrasonic cutter with specific structural size requirements is difficult to be designed in engineering practice an efficient design and analysis method for the structural optimization and vibration characteristics of the clamped combination ultrasonic cutters was established. Methods The method was based on the design requirements of an engineering practice ultrasonic cutter and a combination ultrasonic cutter was designed with a stepped variable amplitude horn and a fixed gradient blade body clamped by the structural dimension parameterization. The study analyzed the influence of the single structural size factor of the ultrasonic horn on the vibration characteristics of the finite element modal inherent longitudinal vibration frequency and output deformation size of the combined ultrasonic cutter reasonably selected the range of structural size values constructed a four-factor two-level full-factor simulation experiment conducted a multi-structural factor interaction analysis and established a resonant frequency regression equation with significant factors. Based on this with the simple harmonic resonant frequency as the target the 28 kHz clamped ultrasonic cutter was designed and optimized. Results Through finite element modal analysis and harmonic response analysis the consistency of the optimized ultrasonic cutter in the inherent longitudinal vibration and resonant frequency with the target design was verified. The simulation output amplitude met the ultrasonic cutting amplitude requirements and the simulation maximum equivalent force was much smaller than the safe allowable yield strength of the material. The consistency of the experimental test frequency with the design and simulation frequency was verified through CNC machining and impedance testing and the impedance value met the design requirements. The ultrasonic cutter was installed into the cutting system for processing experiments and through comparison with ordinary tools laser and other processing methods the designed cutter had stable output frequency and amplitude good cutting quality and high efficiency. Conclusion The results show that the proposed ultrasonic cutter design simulation analysis and other methods have good guidance for the design optimization and engineering application of complex cutters with specific dimensional requirements.