Coating is an efficient and cost-effective method for material protection, but traditional coating techniques often suffer from high costs, poor adhesion, and insufficient density. Cathode plasma electrolysis deposition, a surface treatment and material preparation technology that combines traditional electrolysis with plasma processes, offers distinct advantages in energy efficiency, coating density, and adhesion strength. In this study, Q235 carbon steel was successfully coated by optimizing process parameters. The coating’s surface morphology and composition were analyzed using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), showing significant changes in microscopic particles and surface roughness with increasing voltage and duty cycle. Corrosion resistance was assessed using electrochemical impedance spectroscopy (EIS), and the results indicated that the optimal corrosion resistance was achieved at a voltage of 100 V, a deposition time of 20 min, and a duty cycle of 70%.