Abstract: The crack angle of the abrasive pattern of rubber is closely related with the abrasive pattern generation and wear mechanisms of rubber. Thus it is of great importance to determine the crack angle of the abrasive pattern of rubber. Based on the relation between the fractal dimension of worn surface of rubber and the crack angle of the abrasive pattern, a fractal method to determine the crack angle has been established. It has been found that the crack angle in unsteady state of rubber abrasion for styrene butadiene rubber (SBR) and nitrile rubber (NBR) is almost unchanged; however, that in steady state decreases with normal load increasing.