The invention relates to the field of medium-voltage switching devices, in particular to a medium-voltage load switch assembly tool in a gas tank of a ring network cabinet, and aims at solving the problems of low efficiency and high labor intensity of an existing gas-insulated ring network cabinet load switch when arranged in the gas tank. A support platform, a support frame, a front upright post, a front beam and a rear bracket are adopted, wherein the support platform and the support frame are provided with two-way screw rods; and the height of the support platform is adjusted through adjusting bolts, thereby achieving installation and alignment of the load switch. An LED lamp is also arranged, so that the internal lighting condition of the gas tank is improved and assembly of the load switch is facilitated. The assembly efficiency of the load switch in the gas tank is improved and the labor intensity of a worker is reduced.