Abstract Tokamak is an experimental fusion device in which hightemperature toroidal plasma is produced, it belongs to the category of complicated modern electro-physical facilities. CT-6 is the first small tokamak device in operation in our country, its main parameters are as follows: major radius R: 45cm; minor radius a: 9.2cm; toroidal magnetic field: 2TL; plasma current Ip: 30 kA. After careful test operation and adjustment design goal had been achieved and stable hot toroidal plasma with electron temperature about 250 eV was produced. CT-6 device consists of electro magnetic system (toroidal, Ohmic heating and equilibrium field systems), ultra-high vacuum system (toroidal vessel and pumping system), power supply and control system, diagnostic system. It is designed, developed and operated jointly by Institute of Physics and Institute of Electrical Engineering of Academia Sinica, in collaboration with many other institutions.In the present article the design, structure, engineering development, and also relevant results given by the test operation of CT-6 device are described.