Methane steam reforming (MSR) technology is one of the promising methods of hydrogen production and already available at an industrial scale, in which steam is added to methane to generate hydrogen. MSR carries out at a temperature of 500°C when catalysts and Pd-based membrane reactors are used. The nuclear steam supply system (NSSS) of a modular high-temperature gas-cooled reactor (MHTGR) can provide high-quality steam of around 570°C, which is an excellent heat source for MSR. MHTGR is a typical small modular reactor (SMR), of which the coolant is helium, and the moderator and structural material are graphite. The number of the MHTGR can be decided based on the thermal power required for MSR and electricity generation. In this paper, a six-modular MHTGR nuclear power plant with 1500MW thermal power coupled with the MSR process is designed. The hydrogen production rate is 9.72 tons per hour. The dynamic modeling is based on conservation laws of mass and energy. To examine the dynamic characteristics of the nuclear hydrogen production plant, open-loop responses of the model under different disturbances are presented.