To better understand the origin of the magnetism in pure carbon materials, the research group in Shanghai Institute of Applied Physics (SINAP), The Chinese Academy of Sciences (CAS), has worked out an experimental method to induce macroscopic magnetization, as large as 9.3emu/g, at room temperature in the highly oriented pyrolytic graphite samples by using 70keV 12C+ ion implantation. The ferromagnetic critical temperature, Tc, of the samples is about 460K. The implantation induced magnetic moments in the samples can be tuned simply by changing the implanted ion dose. The electronic structures of the graphite lattice containing magnetic defects that mimic the defects produced by 12C+ ion bombardment are obtained by using spin-polarized density functional theory. The theoretical results support the recent experimental finding. The relative paper has been published in Advanced Materials [H. Xia et al., 2008, 20, 4679-4683]