The invention relates to a transmission section dynamic monitoring method based on an expert system. At first, the invention manually inputs the equipment and the parameters of the electric network, establishes the basic parameter database of the electric network, and then converts the parameters into the expert database in the D5000 system, and sets multiple alarm values. In the actual operation,the system obtains the real-time operation mode through the real-time data uploaded by SCADA and the safety device, and the system compares it with the expert database. When the system exceeds the given value set in the expert database, the system will alarm and give the auxiliary adjustment strategy, and the dispatcher adjusts according to the given adjustment strategy. The invention can providereal-time operation status and pre-decision information for dispatching operators in a very intuitive and vivid form, thereby effectively improving the control of the dispatching operators on the power network and enhancing the ability of the dispatching operators to control the large power network.