Abstract: The electromagnetic emission generated by power electronic equipment is usually at a lower frequency range,according to the testing requirements for the performance of the electrical equipment on GB/T6133.1, the only need to measuredusually is the conducted interference. This paper details the structure, principle, classification and work characteristics of theimportant auxiliary equipment which is the line impedance stabilization network LISN (Line Impedance Stabilization Net-work) inthe EMI test of the power electronic equipment；and described respectively the use methods in the common-mode interference anddifferential-mode interference measurements； indicated the principles of using the LISN in the actual measurement process