<正>In 2004 , 200 kV heavy ion accelerator was operated for 850 h for the study on ion implantation modification. Some improvements and maintenance of the accelerator were made. 9 species of ion beams were provided . They are H+, C+, N+, Ar+, Ar2+, Ar3+, Fe+, Mo+ and Er2+. In these ion beams, 220 keV Er2+ beam is a new rare-earth metal ion beam provided by this accelerator. In 2004, 13 physics experiments were performed on this accelerator. The main experiment are as follows :