The invention discloses a system for positioning a turn-to-turn insulation defect of a dry air-core reactor. The system comprises a first voltage-regulating transformer, a protective resistor, a rectifying silicon stack, a charging capacitor, a choke inductor and a compensation capacitor which are sequentially connected in series to constitute a closed loop, wherein the protective resistor is connected with the first output end of the first voltage-regulating transformer, the compensation capacitor is connected with the second output end of the first voltage-regulating transformer, one end of a discharging sphere gap is connected between the rectifying silicon stack and the charging capacitor, the other end of the discharging sphere gap is connected with the second output end of the first voltage-regulating transformer, the compensation capacitor is connected with a second voltage-regulating transformer in parallel, an alerting-current power supply is connected with the second voltage-regulating transformer and the first voltage-regulating transformer, a first detection point connected with one end of the dry air-core reactor is arranged between the charging capacitor and the choke inductor, and a second detection point connected with the other end of the dry air-core inductor is arranged between the compensation capacitor and the first voltage-regulating transformer.