A segment display device includes: a housing including an upper, cover and a lower cover connected to the upper cover, the upper cover defining a plurality of upper connection holes and a display window, the lower cover defining a plurality of lower connection holes at positions corresponding to the upper connection holes, the upper connection holes and the lower connection holes being configured for connecting the housing, to a building block, and the housing defining an interlace opening; as circuit board arranged within the housing and including a first circuit port and a second circuit port, the first circuit port and the second circuit port being located at the interface opening; and a segment display arranged on the circuit board at a position corresponding to the display window.