The present application provides a top cap assembly and a battery structure. The battery includes a housing including a mounting hole, and the top cap assembly passes through the mounting hole of the housing. The top cap assembly includes a pole, a sealing element, and a plastic element. The pole is provided with an annular groove recessed in a radial direction. The sealing element is sleeved on the pole and positioned in the annular groove. The sealing element is sandwiched between the housing and a groove wall of the annular groove, and the sealing element is partially positioned outside the housing. The plastic element is sleeved on the sealing element and positioned outside the housing, and the plastic element is partially sandwiched between the housing and the groove wall of the annular groove.