In order to ensure the safe operation of power systems, human pay attention to the diagnosis of heat fault of power system widely. When high-voltage bus bar runs overlade or the contactors of high voltage switches contact badly, the contact resistances will become larger, and it would glow if there is load current. Moreover, the phenomenon will cause insulation, aging and even breakdown; in that case, short circuit will occur with major accidents, causing major economic losses. The online and non-contact infrared temperature measurement of high-voltage switch contactors device is designed based on above reasons, and it is mainly composed by the infrared thermopile sensor and focusing lens, etc. Its measured distance is up to 10 meters, and the measured data is transmitted to monitoring center by wireless model. The test indicates that the measurement accuracy can be achieved within 2 degrees, meeting the requirements of online measuring the temperature of switch contactors.