In the past, typical primary return air systems were basically used in various types of electrical buildings in nuclear power plants, while only sensible cooling load existed in the plants, with latent load entirely supplied by fresh air. The integrated treatment of heat and humidity cannot achieve precise control of temperature and humidity, and there is a risk of uncontrolled humidity during the transition season in 100% fresh air mode. Additionally, the lack of intelligent control results in high energy consumption throughout the year. To address the current situation of the above issues, an annual intelligent fresh air ventilation, cold and heat recovery, and dehumidification technology for nuclear power plants is proposed, including high-efficiency salt mist removal technology, high-efficiency heat pipe cold and heat recovery technology, high-efficiency dehumidification technology for fresh air, and intelligent control technology. Secondly, by constructing a test platform, experiments are carried out on salt mist removal efficiency, heat recovery efficiency, dehumidification performance and intelligent control. The results indicate that the efficiency of salt mist removal is greater than 90% by using the baffle plates; horizontal heat pipes can satisfy efficient energy recovery in both winter and summer; vapor compression refrigeration cycles can achieve isothermal dehumidification through condensation heat recovery; The system automatically adjusts the fresh air operation mode based on indoor and outdoor enthalpy values and humidity parameters, which can fully utilize the natural cooling capacity of fresh air and improve the level of system intelligence. This technology can be applied in the intelligent VAV system with independent temperature and humidity control of subsequent Hualong projects.