The invention discloses a wireless temperature measuring system for online substation monitoring. The wireless temperature measuring system comprises a master station, a concentrator, a 3G (three generation) monitoring camera and at least one wireless temperature sensors. The master station and the concentrator are in communication connection through the 3G network. The wireless temperature sensors are in communication connection with the concentrator through short-range wireless communication. The 3G monitoring camera and the concentrator are in communication connection through the 3G network. Online monitoring and automatic alarm of temperature for substations are realized. The radio frequency communication technology and the 3G communication technology are combined to realize online monitoring and reporting of remote data and automatic alarm for abnormalities, manpower routing inspection is omitted, and data reporting is timely, accurate, timesaving and laborsaving.