Abstract As an important detection means of partial discharges, range sensor is widely used in power system in China. Due to the complex and open environment around covered conductor overhead distribution networks, misjudgement and leakage in long-distance of traditional ultrasonic sensors often occur. Aiming at this problem, an range sensor with high sensitivity and directivity is designed in this paper. In this paper, the theoretical model of the ultrasonic screening can is established by COMSOL simulation software, and the structure of the screening can is designed reasonably by analyzing the concentr-ation and directivity of the sound field of the model. In addition, based on the ultrasonic characteristics generated by partial discharge of overhead insulation wire, the ultrasonic probe with a central frequency of 40kHz was selected, and an amplification and filtering circuit was designed to reasonably improve the signal-to-noise ratio of ultrasonic detection signal. The results of laboratory test and field application show that the sensor can accurately detect and locate the partial discharge of covered conductor overhead distribution networks.