In order to improve the safety and stability of Guangzhou power grid, a power transmission line monitoring system using big data technology is proposed based on analysis of the lightning activities in Guangzhou area in recent years and summary of the operational status of power transmission lines and tripping by lightning in Guangzhou power grid. The transient effect on voltage and current around the tripped transmission line can be presented for analysis directly with 3D simulation system to visualize the tripping events and the affected substations. Meanwhile, the big data mining technologies are applied to analyze the correlating factors of tripping events with transient voltage and lightning events, and search for any potential links among them. The proposed system can establish a correlative information database of lightning, tripping and other related factors for Guangdong power grid, and provide effective technical support for making protection principles of grid operation, carrying out daily maintenance of lightning protection, and improving the operation level of the grid.