Abstract: In order to solve the problems of high cost,un-convenient installation and low-precise detection caused by using IR temperature sensor and fiber sensor to detect temperature of isolators in high-voltage distribution equipment at present,an on-line monitoring device of temperature for isolators in high-voltage distribution equipment based on nRF905 was designed,and design of hardware and software of the device was introduced in details.The experimental results showed that circuits of data collection,data receiving and sending and data processing of the device are reasonable,and the device can realize on-line monitoring of temperature of isolators in high-voltage distribution equipment,which has error below(± 1.5 ℃) and meets actual needs of engineering.