<p>With the development of aerospace equipment towards lightweight and high-precision, thin-walled components are widely utilized in the aerospace industry due to their lightweight, high strength, and compact structure. However, their thin-walled nature and intricate geometries impose higher demands on machining accuracy and surface integrity. Ultrasonic-assisted machining, as an advanced machining technology, has demonstrated significant advantages in enhancing machining precision. However, during the machining of thin-walled parts, time-varying cutting loads can easily cause resonance frequency drifts in piezoelectric transducers, thereby affecting machining stability and accuracy. To better utilize this technology, it is crucial to establish a model for the transmission of cutting forces within the transducer system. To address this gap, this study goes beyond traditional cutting force research methods and delves into the internal transmission mechanism of cutting forces within the transducer system. Firstly, the source and time-domain characteristics of axial force were analyzed to construct a load input model. Then, the transducer system was decomposed into key interfaces, including tool-horn, horn-piezoelectric stack, stack dynamics, and stack-back cover, and dynamic models were established for each part based on the electromechanical equivalence principle. Subsequently, the subsystems were coupled in the time and frequency domains to derive an overall model for the transmission of cutting force within the transducer system. Finally, experiments and finite element simulations were conducted to validate the proposed model, demonstrating that the predicted forces matched the simulated forces within a deviation of less than 8%.</p>