Magnetic field-line reconnection is experimentally achieved by quickly reversing the toroidal current in a Tokamak. The evolution of the reconnection depends on the initial plasma parameters. The reconnection occurs in a boundary region between the forward poloidal magnetic fields formed initially and the reversed poloidal magnetic fields generated by the reversed current. When an X-ray separatrix becomes apparent in the magnetic flux function, the local plasma pressure and electron temperature are sharply increased. The reconnection layer penetrates into the plasma core with a speed much slower than the Alfven speed but the reconnection is completed within a time shorter than the classical magnetic diffusion time.