Stable air layers can be formed by injecting air into underwater vehicle surfaces, effectively reducing the wetted surface area and frictional resistance. Ventilating the bottom of the underwater vehicle with baffles to enhance stability is a frequently employed approach to forming a stable air layer. Air layer persistence refers to the phenomenon where the air layer can stay stably at the model's bottom for a period after ventilation ceases. This study focuses on the phenomenon of air layer persistence in the air layer drag reduction technology for underwater vehicles, and the influence of the air ventilation duration on the air layer persistence is investigated through experiments. The evolutionary process of the air layer could be categorized into three distinct stages: growth stage, persistence stage, and slip stage. The durations of the entire evolution and persistence stage are termed total air layer duration and air layer persistence duration, respectively. Statistical analysis of 18 test conditions (each repeated over 900 times) demonstrated: 1. Both probability density functions of total air layer duration and air layer persistence duration exhibited marked right-skewness, with the skewness coefficient of air layer persistence duration serving as an effective metric for evaluating persistence intensity; 2. There exists an optimal persistence intensity when the air ventilation duration is 0.3 s; 3. Beyond the air ventilation duration of 0.43 s, the evolutionary pattern of the air layer converges to the continuous ventilation condition. These findings statistically elucidate the correlation between air ventilation duration and air layer persistence, providing support for the optimization of air layer drag reduction parameters.