The intelligent variable air volume (VAV) system has superior energy-saving performance and can achieve flexible temperature control in different zones under partial load. However, the VAV system has uneven airflow organization under partial load, which poses a potential risk of local overheating. Therefore, further analysis, improvement, and verification of the safety and reliability of the nuclear island VAV system are needed. This article first analyzes the load characteristics of unsteady state users on nuclear islands and the design characteristics of VAV systems used in nuclear power plants. From the perspectives of mechanical and control characteristics, the differences and design points between VAV terminals for nuclear power plants and those for civilian applications are analyzed. Secondly, a test platform for VAV systems in nuclear power plants is established. Through visualized airflow organization experiments, the dynamic response characteristics and airflow organization effects of VAV terminals are studied to evaluate the stability, reliability, and applicability of the VAV system under specific environmental conditions in nuclear island. Finally, to address the issue of uneven airflow organization in VAV systems under partial load conditions, dynamic airflow organization simulation and optimization are conducted. This provides theoretical and experimental support for the first application of the VAV system in the subsequent nuclear island of Hualong. On the basis of ensuring the inherent safety, the systems’ level of intelligence is improved.