The invention relates to an impulse withstand voltage testing device for GIS devices of transformer stations. The impulse withstand voltage testing device for the GIS devices of the transformer stations comprises an impulse voltage generating device, power source accessories and a carrying platform. The impulse withstand voltage testing device for the GIS devices of the transformer stations is characterized in that the impulse voltage generating device is composed of a direct-current power source, resistors, capacitors, an inductor and fixed triggering gap switches in a connected mode, wherein the direct-current power source is connected with the capacitors in three-level parallel connection, and the fixed triggering gap switches through the resistors, and then is connected with a capacitive tested object in series through the inductor to form a tank circuit, and the impulse voltage generating device and the power source accessories are arranged on the same carrying platform. Due to the facts that the fixed triggering gap switches are adopted by the impulse withstand voltage testing device for the GIS devices of the transformer stations, and a transmission mechanism does not exist, debugging is not needed, and the defect of abnormal discharging of a discharge sphere gap can be effectively overcome. The impulse withstand voltage testing device for the GIS devices of the transformer stations is compact and reasonable in structure, and easy and convenient to operate, saves manpower and material resources on a test site, reduces the time for operation, and improves working efficiency.