Solid state heat storage technology has positive significance in consuming surplus electricity from the power grid, balancing peak and valley loads, and reducing environmental pollution by converting nonpeak electricity into thermal energy. In response to the problem of uneven heat extraction in existing solid heat storage devices, a new type of structural heat storage body is proposed, which designs an intermediate channel in the ventilation duct. The numerical model of the heat storage body was established by using Fluent. The temperature distribution and the velocity distribution in the ventilation duct of the new heat storage body when releasing heat are studied, and compared with the structure without intermediate connection. The research shows that the middle connected structure improves heat transfer efficiency and reduces heat accumulation phenomenon. Compared with the structure without intermediate connection, the average temperature of the new structure heat storage body is reduced by 37~68 ℃, with a maximum reduction of 22.8%, and the maximum temperature difference is reduced by 27~60 ℃, with a maximum reduction of 48.2%. The middle connected structure reduces the relative standard deviation of flow velocity at the center of the ventilation duct by 45.4%, improving the uniformity of the flow field. The middle connected structure along the vertical direction makes the temperature distribution of the heat storage body more uniform in the vertical direction, and does not deteriorate the temperature uniformity in the horizontal direction.