Abstract: With the increasing depth and scale of mining activities, traditional hydrological monitoring methods have revealed limitations in real-time performance and accuracy. This paper designs and develops a comprehensive online hydrological monitoring system for mines based on a cloud platform. Incorporating advanced sensor technology and wireless data transmission, the system integrates six key modules: data acquisition, transmission, storage, analysis, early warning, and visualization, forming an efficient, accurate, and intelligent monitoring platform. This paper elaborates on the system architecture and module functions, focusing on core features such as real-time monitoring, multi-dimensional data analysis, customizable warning mechanisms, and 3D visualization. The system enables real-time collection and intuitive presentation of key hydrological parameters, including rainfall, borehole water level, and water yield, through 3D models, thereby improving data interpretation and decision-making efficiency. Furthermore, the system supports dynamic threshold settings and triggers multi-level alarms promptly upon data anomalies. Field applications have demonstrated its stability, accuracy, and responsiveness, providing a valuable technical reference and practical case for the intelligent development of mine hydrological monitoring.