The construction cost of nuclear power plays a decisive impact on the economic benefits of nuclear power enterprises. Under the guidance of the market, nuclear power enterprises have increasingly urgent demand for nuclear power projects with better construction quality, faster progress and lower cost in pursuit of higher profits. The general contracting company of nuclear power projects has accumulated rich experience in project management, but the cost of fine management is still insufficient, except from a deeper level to tap the potential of nuclear power engineering construction cost control. This paper conducts an analysis based on the key points of cost control during the construction cycle of the “Hualong One” project. By examining the project cost data, effective strategies can be distilled, and the deficiencies in cost risk control for various phases can be identified. The nuclear power construction phases covered in the paper encompass: the pre-construction phase (prior to FCD-18), the initial phase (FCD-18 to FCD + 0), the early construction phase (FCD + 0 to FCD + 12), the middle construction phase (FCD + 12 to FCD + 42), the late construction phase (FCD + 42 to FCD + 60), and the final phase (after FCD + 60). This provides a practical foundation for subsequent project cost and risk management planning.