In application scenarios that require stop-on-target behavior and controllable micro-displacements, ultrasonic micromotors (USM) typically achieve high-precision positioning through stepping operation. However, during actual stepping, deformation of the stator surface introduces detection errors in the capacitive angular sensor, thereby limiting the positioning accuracy. To address this issue, this paper focuses on an ultrasonic micromotor with specialized structural features and proposes a stepping control method that explicitly accounts for the initial stator deformation error. First, based on the sensor structure and the principle of a parallel-plate capacitor, the formation mechanism of angular detection errors during the start-stop phases is analyzed. The variation of the rotor-stator gap induced by the excitation and attenuation of the traveling wave in these phases is identified as the main source of error. Accordingly, an error-compensation scheme combining pre-excitation compensation and braking-parameter calibration is proposed. Second, for this type of ultrasonic micromotor, an input-output mapping is established between the excitation voltage frequency, amplitude and phase and the rotational speed, and the voltage amplitude is selected as the control variable. In the closed-loop stepping strategy, taking into account the actual output characteristics of the capacitive angular sensor, a commutation-free, smoothly transitioned stepping scheme is designed. The peaks and troughs of the capacitive waveform are selected as reference points for angle detection, and a nonlinear proportional integral derivative(PID) controller with a tracking differentiator is introduced to realize unidirectional forward trajectory planning, while adaptive adjustment of the voltage amplitude is employed to achieve precise tracking of the angular position. Finally, an experimental platform incorporating a high-precision photoelectric autocollimator is constructed. Experimental results show that the pre-excitation compensation reduces the amplitude of capacitance fluctuations by approximately 82%; in 30 trials of 12° stepping experiments, the control error remains below 0.2°, representing an improvement of about 33% compared with open-loop control, and no error accumulation is observed.