Abstract: Rapid cycling synchrotron (RCS) is a key accelerator of the China Spallation Neutron Source (CSNS), and the vacuum chambers for quadrupole magnets in RCS are alumina-ceramic. The sputtering-system was developed for TiN coating of the chambers. Magnetron sputtering was adopted. The metal screen was installed on the outer surface of the long straight insulating pipe, so it could provide a coaxial electric field with the cathode by DC power. This approach is convenient and practical, and is a very good solution to the coating uniformity. The Ti/N ratio is in 0.9-1.1, the film thickness is around 100 nm, and the adhesion between film and substrate also meets the requirements. The design specifications are generally achieved.