The invention which relates to a movable chlorine dioxide dosing device for the emergent water treatment belongs to the field of sudden tap water or sewage accident onsite rescuing devices. The device which comprises a casing, a medicine pot, an activating agent pot, an activator, metering pumps, a water injector and a pressurized water tube is characterized in that: the medicine pot, the activating agent pot and the activator are arranged in the casing; the medicine pot and the activating agent pot are respectively connected with the activator through a pipeline which is provided with a control valve and the metering pump; the activator is connected with the water injector through a pipeline which is provided with a control valve; and one end of the water injector is connected with the pressurized water tube. The device which can be conveniently and timely used for the sudden tap water or sewage accident onsite treatment allows a no treatment device case caused by sudden accidents to be avoided, the pollution to environment and the energy waste to be effectively reduced, units without installation conditions to be disinfected and preoxidized, and the installation time to be saved by conveying the device to the dosing site when the device is used.