The invention aims at providing an effective tail gas treatment device of a low speed machine. The effective tail gas treatment device comprises an ammonia water injection device, a catalyzing device,a catalytic oxidation device, a cooler, a particulate filter, a carbon dioxide adsorption tank, a drying tank and an activated carbon adsorption tank which are connected in sequence, wherein a liquidstorage tank is arranged above the ammonia water injection device; a spraying head is arranged below the liquid storage tank; the catalyzing device comprises an ammonia diffuser, an ammonia catalyticconverter and a silencer which are connected in sequence; the ammonia diffuser is connected to the ammonia water injection device; the silencer is connected to the catalytic oxidation device; the cooler adopts a water cooling manner; the particulate filter adopts a disposable paper filter; an inlet of the ammonia water injection device is connected to a tail gas inlet pipe; and an outlet of the activated carbon adsorption tank is connected to a tail gas discharging pipe. The effective tail gas treatment device is simple in structure, can effectively remove nitric oxides, CO and hydrocarbons in exhaust gases by the technical measures, has high-efficiency filtrabilitiy for the particles in the exhaust gases, can also adsorb stink in the exhaust gases and enables diesel tail gases to reach emission standards.