<p>Cracks and water seepage are common structural safety hazards in excavation and pit support system. Traditional methods usually rely on a lot of manpower and material resources, and there are some problems in the monitoring process such as low efficiency, long time, incomplete data collection and insufficient accuracy, which cannot meet the needs of modern engineering construction. In recent years, the construction industry has gradually changed to the trend of intelligence and automation, and machine vision has entered the field of vision. It can not only effectively reduce labor costs, but also improve the overall accuracy of monitoring. However, previous machine learning framework usually uses a two-stage monitoring method, which takes a long time including the collection and process of data separately. This paper focuses on pit support systems and provides an overview and comparison of the application of machine vision and machine learning technologies. Furthermore, a real-time defect detection method based on the improved YOLOv8 algorithm, which can process the collected crack data and water seepage pictures, give the physical characteristics of the crack, and mark the location of water seepage, has been proposed and verified. Additionally, a practical project in Huzhou serves as a case study, where the established method has been applied. The actual implementation shows that the model also has good robustness under complex foundation pit conditions.</p>