The invention discloses a method for recognizing an AC cross section in strong correlation with DC transient stability, and belongs to the field of power systems and automation technology thereof. The method calculates a transient stability margin index of an image of a system in a generator grouping mode of taking the AC cross section as a cut set cross section under the condition of DC disturbance at different degrees based on the transient stability time domain simulation results under DC typical disturbance, carries out the further fitting of the change rule of the transient stability margin index of the specified image of the system along with the DC disturbance, and further recognizes the AC cross section in strong correlation with the specified DC transient stability and the quality of strong correlation. The method brings convenience to a power system dispatcher to master the internal operation rule of a complex system, proposes a basis for the coordination and making of an AC/DC coordinative control decision, and improves the effectiveness and automation level of safe and stable control of an AC/DC compound system.