<p>Grinding force is a critical parameter in the grinding process, as it is intimately associated with various factors, including workpiece surface roughness, grinding temperature, specific energy consumption, and grinding wheel longevity. The proposed grinding force model incorporates the material softening effect induced by ultrasonic vibration and the void cutting phenomenon resulting from trajectory overlap. Furthermore, based on a grinding wheel model featuring randomly distributed abrasive grains, the non-productive grinding area arising from void cutting between abrasive grains is considered, leading to the formulation of an actual grinding area model. By employing a refined Johnson–Cook constitutive equation and accounting for the material softening effect induced by ultrasonic vibration, an ultrasonic grinding force prediction model is developed. Subsequently, a comparative analysis is conducted between the experimental results of ultrasonic grinding and the model’s simulation outcomes. The analysis reveals an average relative error of 19.78% for tangential grinding force and 17.72% for normal grinding force.</p>