A crystal growth model of freestanding thick diamond film was discussed,and on the basis of this model,a self-standing thick diamond film slice of a thickness of about 0.6mm was prepared by means of HFCVD ( Hot-Filament- Assisted Chemical Vapor Deposition) method.Then,a friction experiment of the film slice was conducted on a ball-disc tribometer,and the tribological properties of the film slices respectively with a steel ball,a ceramic ball and an aluminum ball as the friction pair were characterized by using a SEM and a Raman spectrometer.The results show that ( 1) when the friction pair is an aluminum ball,average friction coefficient is the biggest and metal transfer layer appears very fast in the initial stage of grinding; ( 2) when the friction pair is a ceramic ball,the average friction coefficient is the smallest and the ball surface material is in a fine clastic distribution; and ( 3) the wear of the film slice is very small after the experiment,which means that the film slice is a good wear-resistant material.