Provided is a top cover structure for power battery, including a first electrode assembly, a second electrode assembly, a top cover plate electrically connected with the first electrode assembly, and a deformable plate attached to the top cover plate; the second electrode assembly includes a second electrode terminal, a second connecting block, a second insulating piece in which a via-hole and an gas-guide hole are defined, an upper sealing piece arranged between the second insulating piece and the second connecting block and including a sealing area for deforming space and a sealing area for electrode terminal, and a lower sealing piece arranged between the second insulating piece and the top cover plate and enclosing the via-hole for deformable plate. The sealing area for deforming space encloses the via-hole and the gas-guide hole, the sealing area for electrode terminal enclose the second electrode terminal.