Nitrogen Oxides(NOx) in the atmosphere cause serious environmental problems. such as photochemical oxidant, acid rain, and global warming, so they have to be controlled before emitting into the atmosphere. In this paper, Selective catalytic reduction(SCR) of NOx with C3H6 was studied in the presence of oxygen. The SCR catalysts were prepared by double wash-coat onto monolith. The lower layer consisted of Au/Al2O3 or Pt/Al2O3 and the upper layer was coated with mordenite onto the lower layer. The Au and Pt particles were dispersed uniformly on monolith with 4~5nm. The activity of SCR catalysts was investigated studied with varying the loading of noble metal in the lower layer, contact time, and NOx concentration. CuM//Au(5wt%)/Al2O3/M catalyst and CuM//Pt(1wt%)/Al2O3/M catalyst are very efficient for the Nox reduction. the activity was greatly enhanced by coating the upper layer. Also, the reaction temperature taking the maximum activity was lowered by 50℃~100℃, and temperature window was broadened, optimum loading for Au and Pt on the lower layer were 5wt% and 1wt%, respectively. The activity was linearly increased with contact time. As a result, the double wash-coat monolith catalyst could be considered to be a promising system for SCR of NOx with C3H6.