The aim of this work was to analyze the causes for condensation generated in plastic crates of ammunition, and explore approaches to eliminating condensation. In alternating hot and humid environment, temperature and humidity changes in the plastic crates were measured and evaluated after the implementation of the following methods to eliminate condensation, improved sealed form of caisson(method A), improved sealed form of caisson and placed moisture agent in the crates(method B), improved sealed form of caisson, placed moisture agent in the crates and reduced the moisture content in the products pre-packaged and the packaging material (method C). After taking the three measures, the average humidity at 20 ℃： A reached 85%, and continued to increase; B reached the balance point of 72%; C maintained at about 51%. Therefore, reducing the moisture content in the packaging material and products pre-packaged, placing moisture agent in the crates and improving the sealed form of caisson, could block the outside air leakage, maintain the relative humidity level of 50% in the caisson for a long time, which could effectively reduce the generation of condensation, and guarantee the quality of ammunition during storage.