Based on the previous research work, Sn, Bi, Ti, Sb and other alloying elements were added to the Al-Zn-Ga-Si low-potential sacrificial anode material to improve its overall performance of the anode. By conducting the electrochemical performance test in the conventional seawater environment, a sacrificial anode material with a low driving potential, that meets the requirements, is selected from a variety of prepared anode materials. The selected Al-Zn-Ga-Si-Sb anodes with good comprehensive electrochemical performance were further assessed in a simulated alternating depth and shallowness of seawater environment, especially in terms of its electrochemical performance, while the influence of Sb content on the electrochemical performance of the anode was also investigated through electrochemical performance test and three-dimensional video observation. The results show that the addition of an appropriate amount of Sb can promote the uniform activation and dissolution of the anode materials, therewith improve the activation performance of anodes in complex environments, and reduce the effect of local corrosion. When the Sb content is 0.5% (mass fraction), the comprehensive electrochemical performance of the anode is good and meets the requirements in accord with the general cathodic protection guidelines for high-strength steel. Thus, it may be expected that the Al-Zn-Ga-Si-0.5Sb sacrificial anodes can further be developed to meet the requirement for the high-strength steel cathodic protection in alternating depth and shallowness of seawater environments.