In order to systematically evaluate the activities of the noble metal catalysts for simultaneous removal of soot and NO_x and the corresponding effect of sulfur and water, a series of noble metal catalysts (Ru／ZrO₂, Ag／ZrO₂, Rh／ZrO₂, Pd／ZrO₂, Pt／ZrO₂, Ir／ZrO₂, Au／ZrO₂) were prepared by iso-volumetric impregnation method firstly. Then the activities of the noble metal catalysts for simultaneous removal of soot and NO_x were measured under oxygen-rich condition, and the effect of SO₂ and H₂O on the performances of those catalysts were also studied. Experimental results showed that noble metal can improve the activities of simultaneous removal of soot and NO_x significantly. Compared with the other catalysts, Ru／ZrO₂, Ag／ZrO_2and Pd／ZrO₂ have higher catalytic activity. The existence of SO₂ and H₂O promoted Ir／ZrO₂ catalystal removal of soot and NO_x simultaneously, promoted Pt／ZrO₂ catalyze for soot oxidation, Ru／ZrO₂ for NO_x reduction and inhibited the catalytic activities of other noble metals.