The invention discloses a GIS (Gas Insulated Switchgear) gas leakage live plugging device. The device comprises a plugging cap and a plugging base; the plugging base is provided with a first cylinder,a second cylinder and a circular truncated cone; the first cylinder is located at the upper end of the second cylinder; the circular truncated cone is located at the lower end of the second cylinder;a first through hole is formed in the first cylinder; a gas collection cavity is defined in the second cylinder; the first through hole is communicated with the gas collection cavity; a cone-shaped through hole is formed in the circular truncated cone; the cone-shaped through hole is communicated with the air collection cavity; an external screw thread is formed on the first cylinder; and the first cylinder is in threaded connection with the plugging cap. According to the plugging device of the invention, the lower end of the plugging device is provide with the circular truncated cone; the cone-shaped through hole is formed in the circular truncated cone; the lower end of the circular truncated cone can be cut and hammered according to the size of a gas leakage point; the circular truncated cone at the lower end of the plugging base can be adjusted to completely cover the periphery of the gas leakage point of a GIS; the first cylinder is in threaded connection with the plugging cap; after the plugging base is fixed on the gas leakage point of the GIS, the plugging cap is screwed on the plugging base, so that the gas leakage point can be plugged under a condition that the GIS is not de-energized.