In order to understand the comprehensive intelligent warning system of the power grid, a research on the comprehensive intelligent warning system of the power grid based on multi-source data fusion has been proposed. From the perspective of big data applications, this paper proposes to establish a comprehensive intelligent warning system for power grid dispatch and monitoring by integrating multi-source application data such as EMS system, fault recording system, OMS system, meteorological monitoring system, and adopting a certain data algorithm model. This system can achieve functions such as monitoring and analysis of power transmission and transformation equipment, defect warning, power grid risk warning, and fault alarm analysis, assist dispatchers in power grid monitoring and fault handling, and effectively improve the level of power grid regulation.