To enhance the corrosion and wear resistance of titanium alloys in marine environments, this study employed ultra-high frequency (≥10 kHz) micro-arc oxidation to treat TC17 titanium alloy. The results indicated that as the working frequency of the pulse power supply increased from 0.5 kHz to 10 kHz, the number of pores on the coating surface increased while the pore size decreased, accompanied by improved coating thickness and density, leading to significantly enhanced corrosion and wear resistance of the coating. However, when the frequency reached 20 kHz, the pore size on the coating surface increased, accompanied by decreased densification, increased defects, and deteriorated performance. High-speed photographic analysis of the discharge process on the surfaces of samples prepared at different frequencies revealed that the cascade discharge phenomenon gradually weakened with increasing frequency when the working frequency did not exceed 10 kHz. Whereas, when the frequency reached 20 kHz, the cascade discharge on the coating surface intensified again, with the duration of cascading discharge exceeding 1800 pulse cycles. Severe cascade discharge may be the primary cause of coating quality deterioration at higher frequencies. This study provides important insights for the preparation of low-porosity, high-density micro-arc oxidation coatings.