As an important part of the world energy system, nuclear energy plays an important role in ensuring the security of energy supply in all countries. After decades of development, the use of nuclear energy has been greatly enriched, not only limited to power supply, but also gradually played a role in the fields of Cogeneration, hydropower cogeneration and so on. The increasingly rich application scenarios of nuclear energy also put forward new requirements for the water production process of nuclear power plants. Based on the actual situation of a nuclear project, this paper introduces the water making process of demineralized water for nuclear engineering units and the water making process of boiler make-up water for heating boiler room, points out the problems existing in the original water making process scheme, analyzes the causes of unqualified steam quality of heating boiler, and puts forward practical solutions, The coupling methods of two product water production processes are discussed, and the influence of raw water quality change on the coupling process is analyzed. The coupling scheme of water production process proposed in this paper can realize the simultaneous production of product water with two kinds of water quality in one production line, effectively reduce the engineering cost of water supply facilities, reduce the floor area, ensure the safety of water supply quality, and provide new ideas and references for the multi-purpose utilization of nuclear energy.