The invention provides a constant temperature tea drying device, and belongs to the field of mechanical equipment for tea processing. The constant temperature tea drying device comprises a fuel storage bin, a first fan, a boiler, a drying box, a feeding device and a tea storage bin, wherein the fuel storage bin and the first fan are connected with the boiler; the boiler is connected with the drying box; the tea storage bin is sequentially connected with the feeding device and the drying box; a heat exchange pipe is arranged on the inner wall of the boiler; the heat exchange pipe is provided with a heat exchange pipe open end and a heat exchange pipe outlet end; a tea output is formed in the bottom of the drying box; a hot air inlet end is connected with the heat exchange pipe outlet end; a hot air outlet end is connected with a first hot air extension branch pipe through a second fan; the first hot air extension branch pipe is further connected with the heat exchange pipe open end; a tea cooling device is arranged below the tea output; and the tea cooling device is connected with the tea output through a cooling pipeline. According to the constant temperature tea drying device, tea drying and cooling after drying can be achieved, constant temperature drying is achieved during the drying process, full-sealing cooling is achieved during the cooling process, and the drying efficiency and quality of tea are improved.