The individual damage on high oriented pyrolytic graphite surface induced by gold ions of 530keV—4.5MeV was studied with scanning tunneling microscope. The hillock-like damage was observed and measured and then the average diameters of the hillocks were obtained. In terms of a modified nonlinear thermal spike model, the diameters of the damage were calculated and the results fit well with the experimental data. The possible mechanism of damage formation is discussed.