Abstract: The Van der Waals corrections in the Van air-gun wavelet models are usually assumed as constants. However, they actually alter with the change in temperature. Through the actual measurement of the gas in the experiment, we utilized the conversion relationship between the virtual coefficient and Van der Waals corrections, and discovered the change value that Van der Waals corrections alter with the change in temperature, and it should not be ignored in the research. The actual gas follows the ideal gas equation approximately at ordinary temperatures and pressures, therefore, we introduced the Van der Waals gas equation. In this research paper, gas in the guns is regarded as a Van der Waals Gas by Van der Waals Gas Theory. Based on the open quasi-static thermo-dynamical system and the bubble oscillation theory, the wavelet model of the Van der Waals Gas is established. The changes of Van der Waals corrections with temperature are analyzed in details, and the wavelet model of the Van der Waals Gas is improved by leading into fitting function. Through analysis and comparison of simulation examples, it manifests that the result of improved model is close to the measured wavelet and relative to that of the wavelet model of the Van der Waals Gas. Thus, the reliability of the improved model is valid, and it will provide the reliable foundation for the further analysis of the air-gun wavelet simulation.