The invention relates to an automobile exhaust purification method and an automobile exhaust purification system thereof. The automobile exhaust purification method comprises the following steps of winding one end of activated carbon paper (41) on active and passive carbon paper rolls (42) in tank bodies (10a, 10b), winding the other end thereof on the active carbon paper roll (43), and winding the part between the two ends on a paper tallying tube (20) on an exhaust channel in an automotive muffler tube (100); when the activated carbon paper adsorbs and is saturated with harmful substances, rotating the active carbon paper roll (43), correspondingly rolling the old activated carbon paper on the paper tallying tube (20) onto the active carbon paper roll, simultaneously driving the passive carbon paper roll (42) to rotate by the carbon paper, releasing and rewinding new activated carbon paper on the paper tallying tube, and stopping rotating when winding one circle of new carbon paper on the paper tallying tube; and when completely releasing the new carbon paper on the passive carbon paper roll, replacing the passive carbon paper rolls and the active carbon paper rolls. The invention utilizes the replaceable activated carbon paper to adsorb the harmful substances in exhaust with lasting effect, does not obstruct exhaust emission and noise damping, and the use of the carbon paper does not cause secondary pollution to environment.