The utility model belongs to the field of diesel engine exhaust aftertreatment. The utility model relates to a catalytic converter, in particular to a mute SCR catalytic converter. The catalytic reaction device comprises a hollow cylindrical catalytic reaction cylinder, a connecting ring is arranged at one tail end of the catalytic reaction cylinder, a fixing ring is installed at the tail end of the connecting ring, a connector is arranged on the front side of the fixing ring, a plurality of forked pieces which are annularly arranged at equal intervals are arranged at the tail end of an air outlet pipe, and an elastic aluminum sheet is further arranged on the fixing ring. According to the utility model, the catalyst carrier is arranged; the purification treatment on the tail gas is realized; when the gas is exhausted from the gas outlet pipe; forked sheet, according to the SCR catalytic converter, each forked piece can be opened by a certain angle, gas is converted from a high flow rate to a low flow rate, so that noise generated when tail gas flows is reduced, in addition, the fixing ring and the clamping ring are fixed through the arranged elastic aluminum sheet, and the problemthat noise pollution is generated when a common SCR catalytic converter works is solved.