A nano-ZrO2 modified coating system was prepared by incorporation of nano-ZrO2 concentrates into phenolic-epoxy resin. The corrosion performance of the coatings was evaluated in hot mixed acid solution, using electrochemical methods combined with surface characterization, and the effects of nano-ZrO2 content were specially focused on. The results showed that 1% and 3% nano-ZrO2 addition enhanced the corrosion resistance of the coatings, while 5% nano-ZrO2 addition declined it. The coating with 3% nano-ZrO2 presented the minimum amount of species diffusion, the lowest average roughness (5.94 nm), and the highest C/O ratio (4.55) and coating resistance, and it demonstrated the best corrosion performance among the coating specimens.