Porous cordierite beads, of which the average pore size was $130{mu}m$ and porosity was about 80%, were prepared by the foaming method and then their application as support of the $Pt/{gamma}-alumina$ catalyst for $NO_x$, reduction with propene was investigated. The pressure drop of a 2 mm porous beads filter was less than that of a 1 mm porous beads filter and the difference in pressure drop between these two increased as the flow rate increased. The catalytic activity of $Pt/{gamma}-alumina$ washcoated on the porous bead was tested with varying Pt loading $(0.005{sim}0.1g/cm^3),;C_3H_6/NO$ mole ratio $(0.5{sim}8)$, space velocity $(20,000{sim}30,000h^{-1})$ and oxygen contents (1 and 8). Pt loading of $0.04g/cm^3$ showed the highest activity for $NO_x$ conversion. The $De-NO_x$, test was operated in the temperature range of $200{sim}400^{circ}C$ and the best operation temperature of the catalytic filter is about $250^{circ}C$. As the C/N ratio increased, increase of the $NO_x$, conversion might result from the increase in exhaustion of the amount of oxygen by the reduction of hydrocarbon. $NO_x$ conversion at $20,000h^{-1}$ of space velocity shows a maximum 34% higher conversion than that at $30,000h^{-1}$. On condition that $O_2$ was 5%, space velocity was $20,000h^{-1}$ and the C/N ratio was 8, the $NO_x$ conversion exhibited a maximum of 40% at $250^{circ}C$.