This paper proposes an intelligent recognition method of transmission section based on cut-vertex and path search. The transmission section is defined according to the characteristics of power flow transfer after the overload branch is cut. By drawing on the conceptions of cut-vertex

block and the shortest path possible in the graph theory

this paper presents an in-deep analysis on the topological characteristic of the transmission section. Through a series of matrix operations

the proposed method will find out the k shortest paths between two nodes of the overload line in a block with overload with the overload line as its center

and finally recognize the transmission section suffering the greatest harm from branch outage. Considerable improvement in power network model dimensionality reduction is reported

and optimal selection of k and path searching algorithm

the value of k and the shortest path determination are given

effectively avoiding omission of the key branch

greatly reducing the analysis computation workload

achieving rapid recognition of the transmission section

and laying a foundation for preventing cascading tripping due to grid faults. Simulation results of a New England 39-bus testing system and an IEEE 118-bus testing system show the correctness and validity of the method.