The coaxial configuration of gas-insulated substations is of great advantages transmitting the electromagnetic wave excitated by partial discharge and of great advantages of partial discharge detection. Based the characteristics of configuration of GIS and PD signals inside, the authors design a disc coupler and a loop coupler for continuous monitoring of partial discharge in GIS, and analyze the sensor's characteristics theoretically. The frequency response (FR) characteristics of the disc coupler and the loop coupler are analyzed by the simulation and measurement realistically of square wave response. In addition, the measured results of partial discharge by the sensors designed in GIS are given, and it is shown that the sensors designed are available for the measurement of partial discharge in GIS.