The invention discloses a heat retainer structure which comprises a shell and a plurality of heat retaining bricks, wherein the shell is formed by piling up a plurality of framework bricks; a heat retaining cavity is formed in the shell and is provided with a fluid inlet and a fluid outlet; the heat retaining bricks are paved in the heat retaining cavity and divide the heat retaining cavity into aplurality of different fluid passages allowing the fluid to flow; the energy storage density of each of the heat retaining bricks is greater than that of each of the framework bricks; and the strength of each of the framework bricks is greater than that of each of the heat retaining bricks. The heat retaining bricks with larger energy storage density are used as the heat retaining/releasing mainbodies, and the framework bricks with larger strength are used as support structures, so that the stability of the heat retainer structure can be improved, and larger energy storage capacity is also realized. The fluid passages are formed through arrangement of the heat retaining bricks in the fluid flowing direction and can be set to multiple forms including linear type, arch and the like according to the actual demand.