In order to master the performance change of ammunition and equipment after long-term storage in shipborne environment, and verify whether the current design and test standards of ammunition and equipment meet the actual use requirements of the equipment, the ammunition of a naval gun was placed in three non-standard storerooms under the conditions of subtropical humid atmosphere and tropical marine atmosphere for 5 years. During the test period, the participating munitions were regularly inspected, and after completing the 5-year long storage test, the munitions were subjected to firing tests for internal ballistic performance, continuous firing performance, etc. by comparing the appearance of the munition after completing the laboratory tests of mould, damp heat and salt spray with that after completing the 5-year long storage test, the firing performance of the munition before and after the long storage test was compared, the performance change of the naval gun ammunition after 5 years storage test was obtained. The results show that after being stored for 5 years in the tropical marine atmospheric environment simulating the shipboard environment, some of the cartridge cartridges and primer are corroded, and the projectiles are corroded or moldy, but there is no obvious change in interior ballistic performance and continuous firing performance of ammunition. After 5 years storage in simulated shipborne environment, the interior ballistic performance and continuous firing performance of the ammunition can meet the requirements of product design and can be used safely. There are some differences between the tropical marine atmospheric environment and the test conditions stipulated in the national military standard. The tropical marine atmospheric environment has obvious corrosion to the appearance of a certain naval gun ammunition under the existing packing conditions.