To balance the intermittent renewable energy (IRE), it is necessary for nuclear power plants (NPPs) to operate flexibly. The flexibility can be given by cogeneration, where the main steam flow are used to drive several thermal loads such as the turbine and seawater desalination process. The electric power of a nuclear cogeneration plant (NCP) can be regulated through adjusting the excess steam flow to the cogeneration processes. Due to the fluctuation of IRE generation, the distribution of main steam to different thermal loads in a NCP varies with net demand frequently, which in turn results in a floating feedwater temperature, and further forms a disturbance to the operation of nuclear reactor. To mitigate the fluctuation of process variables caused by balancing IRE generation, it is necessary to study the coordinated control of flexible nuclear cogeneration plants. In this paper, the scheme of a NCP form by a 200MWth nuclear heating reactor NHR-200II based nuclear steam supply system (NSSS) driving a turbine and a seawater desalination process is first introduced. To balance the IRE generation, a plant coordinated control strategy is newly proposed. The feasibility of this control is verified through numerical simulation, which shows that this NCP can be adopted for balancing IRE.