The invention relates to a GIS same frequency and phase AC voltage withstand test system. The structure of the GIS same frequency and phase AC voltage withstand test system is that an excitation transformer, an electric reactor, a current-limiting resistor and a capacitive divider are connected in turn so that a series resonant loop is formed. The series resonant loop is connected with a frequency conversion cabinet. The series resonant loop and the output end of a sampling device are connected with the input end of a control box. The output end of the control box is connected with the frequency conversion cabinet. The input end of the sampling device is connected with a voltage mutual inductor low voltage side on an operation bus. The GIS equipment AC voltage withstand test system under the condition of no power outage of adjacent buses is established so that performing of a GIS equipment AC voltage withstand test is enabled to be possible under the condition of no power outage of the adjacent buses, and great convenience is provided for performing of the voltage withstand test after expansion and maintenance of the system. The GIS same frequency and phase AC voltage withstand test system is suitable for being widely applied and popularized in an electric power system.