Plastic bottle caps, as the core components ensuring sealing in Baijiu packaging, have developed mature design schemes under normal temperature conditions. However, there is a lack of systematic reference for sealing design under high-temperature conditions for pasteurization. This paper analyzes the mechanism of how high-temperature environments affect the sealing performance of plastic bottle caps, employs a single-variable experimental method, and systematically investigates the influence of sealing structure parameters and material formulations on high-temperature sealing performance, providing a reference for the sealing design of plastic bottle caps under pasteurization conditions.