Nuclear power, as an important clean, low-carbon, and safe high-efficiency energy sources, plays a crucial role in the development of modern energy systems. With the rapid development of nuclear power, there are fewer and fewer available high-quality coastal plant sites, and nuclear power construction is gradually shifting to nearshore areas. Nowadays, seawater recirculating cooling system has become a key technology for nearshore nuclear power construction, due to its lower water resource requirements and higher cooling water utilization. As the recirculating cooling water continues to concentrate, the system is prone to scaling and corrosion, which reduces its operational reliability and safety. Currently, experimental studies on the crystallization behavior of seawater during evaporation in the recirculating cooling systems of nuclear power plants were relatively limited and complex. Moreover, these studies primarily focused on carbonate scaling substances, with a lack of research on sulfate salts, easily soluble salts, and salinity. This study employed advanced characterization techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS), to analyze the composition and content variation of scaling substances at different concentration rates during seawater evaporation crystallization. The study also explored the restricting effects of non-carbonate scaling substances, easily soluble salts, and salinity on increasing the concentration rate. The findings provided theoretical and technical support for determining the optimal concentration rate and water treatment solutions for the seawater recirculating cooling systems in nuclear power plants.