Inter-turn short circuit is the most significant fault type in dry-type air-core reactors, and there is currently a lack of effective monitoring methods, leading to a high failure rate of dry-type reactors. To address this issue, this paper analyzes the impact of inter-turn short circuits on the voltage and current of dry-type reactors. By comprehensively considering the phase and amplitude variation characteristics of voltage and current, a method for online monitoring of reactor inter-turn short circuit status based on Lissajous figure characteristics is proposed. Simulation and experimental results show that, compared to power factor monitoring, the proposed method has higher sensitivity to inter-turn short circuits, which helps to further improve the reliability and accuracy of dry-type air-core reactor status monitoring.