Abstract: On the basis of RTCA/DO-160E magnetic effect requirement, it not easy to measure the angular deflect; themagnetic of equipment under test cause the free magnetic deflect, by RTCA/DO-160E magnet effect measure, in this paperangular deflect relate to magnetic intensity and the limit was figured; it not require the cable of equipment under test how to lay,magnetic intensity emit by equipments under test and its cable is measured, and the testing data is close to practical application