Abstract: The monitoring and risk warning system of complex underground excavation is composed of several sub-objects. Traditionally, the control values of monitoring data are determined by construction norms. However, a single control value can only reflect the local properties and safety state of excavation and be easily affected by external interference. Based on data fusion, considering field experience and expert hierarchy system, a brand-new risk warning system in excavation engineering is introduced to give a comprehensive assessment of construction safety. This system is a secondary development product of AutoCAD integrating the excavation site conditions, construction steps of each part, principles of mechanics and monitoring data to conduct static, dynamic evaluation and multi-source data fusion assessment of the current and potential risks. Moreover, a project case is presented to demonstrate that this system can detect more potential risk than the traditional information construction system and enjoy high applicable value.