Abstract: For the complex structures, the narrow space and the large quantity of equipments in the helicopter, a complicated electromagnetic environment makes effects in the avionics platform. For the purpose of finding the ElectroMagnetic Interference (EMI) coupling path rapidly, a method for determining EMI coupling path is presented. Based on the minimum electromagnetic attenuation, the EMI coupling network is converted into EMI coupling diagraph. In a specified frequency, Dijkstra algorithm is applied to seek the shortest path between interfering source and victim. Then a weak link of the electronic system will be determined. Based on this method, a simulation of processors and radio system in helicopter is carried out, and the main coupling path is successfully established. Simulation and analysis indicate that the proposed method is able to find out the weak links of electronic system in an effective way and support for the solution of electromagnetic compatibility issues.