The invention discloses a system and a method for detecting the inter-turn insulation of a dry reactor, belonging to the technical field of high voltage. The system of the present invention comprisesa power module which collects three-phase 380V voltage, converts the voltage and outputs DC voltage, a data acquisition module which collects the DC voltage of the power module and oscillating voltageof a tested product and transmits the collected voltage signal to a control module, a discharge switch which converts the DC voltage outputted by the power module into oscillating voltage, and the control module which controls the system operation, system protection, data analysis and calculation, and the discharge of a discharge switch. According to the invention, by adopting a power electronicswitch as the discharge switch, the stable repeated discharge at up to 380 kV can be realized, and an oscillating voltage waveform required by the winding turn-to-turn voltage withstand tests of 66 kVand 110 kV dry reactors can be generated.