The invention relates to a combined radioactive wastewater treatment device, comprising a selective inorganic adsorption module; an ultrafiltration membrane pretreatment module, comprising an ultrafiltration water inlet tank, an ultrafiltration feed pump, a self-cleaning filter, an ultrafiltration membrane assembly and an ultrafiltration middle water tank which are connected in sequence by pipelines; a reverse osmosis treatment module, comprising a reverse osmosis feed pump, an ultraviolet sterilizing lamp, a security filter, a first-stage reverse osmosis assembly and a second-stage reverse osmosis assembly which are connected in sequence by pipelines; a continuous electrodeionization fine treatment module, comprising a first-stage continuous electrodeionization device and a water production tank. According to the combined radioactive wastewater treatment device, a combination of multiple processes is adopted, process selection can be performed according to the characters of inlet water, and resin type secondary wastes are not generated by the treatment device; the treatment device is movable, so that the treatment device can be not fixedly arranged at one place, thus improving the radioactive wastewater treatment capacity of a nuclear power plant in a nuclear emergency state; the whole treatment device has the advantages of small size, low energy consumption, high decontamination coefficient and convenience in maintenance and change.