<p>Aeration irrigation has garnered significant attention due to its effectiveness in enhancing crop yield and water use efficiency. Understanding the two-phase flow mechanism of water–gas in the aeration pipeline is of great significance for promoting the development of the aeration irrigation system. In this study, a formula for calculating Reynolds number of water–gas flow in aeration pipeline was established by combining theoretical analysis with experimental verification. In addition, based on the YOLO v5 image classification model, a classification and detection model of water–gas flow pattern was proposed. The results show that increasing aeration rate can increase pipeline pressure. The overall accuracy of the developed flow pattern detection software was 86.3%, which can meet the requirements of practical application. Finally, based on image classification and theoretical analysis, the formulas of the corresponding flow patterns were obtained. This study provides a solution for determining the two-phase flow pattern of water–gas in aerated irrigation system, which was of great significance for improving the hydraulic calculation of aerated irrigation system and promoting the wide application of aerated irrigation technology.</p>