In recent years

burnt fault due to inter-turn short circuit of dry type reactor often happens in Gansu power grid. The internal insulation condition of the dry core type reactor can not be judged correctly by the conventional test method. In order to solve this problem

through comparing the distinction of interturn short circuit occurred in the middle and terminal part

the pulse voltage resonance method is studied

and is used in the actual detection work. It is found that the method can effectively detect the internal inter-turn short circuit fault of reactor and lays foundation for the survey work of dry type reactor in Gansu Province.