The present invention provides an inner start-up tool of a conduit bearing capacity reinforcing device and a using method thereof, the inner start-up tool comprising: an outer cylinder in which a pressure bearing disc is axially movably provided, a lower end of the pressure bearing disc being elastically connected with a balance block, and a first ring block and a second ring block being movably diametrically disposed through a lower cylinder walls of the outer cylinder; a first link mechanism having a first vertical rod and a first horizontal rod rotatably connected to the first vertical rod, the first vertical rod being rotatably connected to the balance block, the first horizontal rod being rotatably connected to the first ring block; a second link mechanism having a second vertical rod and a second horizontal rod rotatably connected to the second vertical rod, the second vertical rod being rotatably connected to the balance block, the second horizontal rod being rotatably connected to the second ring block. The inner start-up tool of the conduit bearing capacity reinforcing device and the using method thereof according to the present invention can be used for efficiently operating the conduit bearing capacity reinforcing device, is simple in structure and convenient in use.