In order to study the temperature change of a composite packaging box in the process of low temperature environment, the method of equivalent analysis was used to simplify the modeling of the whole packaging box, and Fluent software was used for two-dimensional model simulation of the heat transfer when the product material parameters inside the packaging box were unclear. The results show that the temperature of the product inside the packaging box decreased by 9.9 ℃ (no more than 10 ℃) after 5 h under the set conditions. The passive thermal insulation performance of the package could meet the requirements and effectively protect the products during transportation.