Targeting at the infantry unit ammunition protection problem in sea-crossing and island-landing operations, a combined amphibious portable protective equipment was designed to improve the ammunition support ability during island landing in wartime. Based on theoretical analysis and engineering design, using the 3D SolidsWorks design tool, ammunition amphibious protective equipment was designed and analyzed. The problems of waterproof, moistureproof, floating on the water and convenient carrying were solved by means of overall structure analysis and key parts design. The design functional requirements were met. Through analysis of typical infantry ammunition loading application, it was shown that the protective equipment could meet the protection requirements of a variety of infantry unit ammunition and provide support for ammunition support in sea-crossing and island-landing operations.