This paper describes system design of the Cluster Test Facility (CTF) which is a test facility to develop high field toroidal coils more than 12T for fusion reactor. The CTF is composed of two Cluster Test Coils (CTC), a 100-l/h helium cryogenic system, a vacuum system, a 3 KA DC power supply and protection system, and a PDP-11/34 computer system for data acquisition and control. The purpose of the CTF is not only to test the Test Module Coil (TMC) which is a test coil to be developed, but also to develop and verify total technology required for superconducting coil system for the tokamak reactor at the Japan Atomic Energy Research Institute (JAERI).
