The work aims to improve corrosion resistance of 7A04 aluminum alloy. Corrosion behavior and rule of 7A04 with different contents of rare earth Ce by simulating marine atmospheric environment with alternate immersion test. Microstructure and inclusion morphology of different samples were observed by using metallographic microscope and scanning electron microscope (SEM). Corrosion dynamic law and electrochemical behavior characteristics of the samples were analyzed in the method of weight loss and electrochemical impedance spectroscopy (EIS), respectively. In the 7A04 aluminum alloy Ce containing 0%, 0.39% and 0.81% Ce, grains were the smallest, second phase or inclusion was the least and evenly distributed, and matrix structure of the alloy was improved when Ce content was 0.39%. Compared to the Re-free 7A04, corrosion weight loss of the 7A04 aluminum alloy containing Ce was significantly lower, and resistance of the rust layer increased, and the alloy containing 0.39% of Ce exhibited the highest resistance of rust layer. Three kinds of 7A04 aluminum alloy are all subject to obvious local corrosion, mainly the pitting. The addition of rare earth Ce changes phase T and S in non-rare earth aluminum alloy, produces new fine massive intermetallic compounds, refines uniformity of structure, increases the resistance of corrosion rust layer, enhances protective capability of the rust layer against substrate and improves marine atmospheric corrosion resistance. Among three kinds of 7A04 aluminum alloy, the one containing 0.39% Ce exhibits the best corrosion resistance.