In order to establish the prediction model of grinding force in ultrasonic assisted helical grinding processes and give full play to the guiding role of grinding force in the optimization of Ti3Al microhole grinding parameters, the changes of cutting deformation forces and friction forces were analyzed under ultrasonic vibrations based on the chip section area theory, and the grinding force model of ultrasonic helical grinding hole was established. The grinding force data were collected and verified with the established model by setting up an ultrasonic assisted helical grinding Ti3Al microhole experimental platform. The results show that the grinding forces decrease with the increasing of spindle rotation speeds and increase with the increasing of feed speeds. When the ultrasonic amplitudes increase from 0 to 1.6 μm, the surface grinding forces and axial grinding forces are decreased by 27.2% and 28%, respectively. The prediction results of ultrasonic helical grinding force model are in good agreement with the experimental data, and the numerical errors are kept within 20%, which provides a theoretical basis for the optimization of processing parameters of ultrasonic assisted helical grinding of Ti3Al microholes. © 2023 China Mechanical Engineering Magazine Office. All rights reserved.