<p>The negative pressure ventilation system, serving as a critical subsystem within the tritium safety confinement system of the compact fusion energy experimental, is responsible for maintaining dynamic confinement functionality over the C2 and C3 confinement subzones during normal operational conditions, thereby restricting the leakage and dispersion of radioactive materials. Consequently, rational and reliable design of the tritium confinement negative pressure ventilation system is of paramount importance. Key aspects of the system process design include determining pipeline network dimensions and evaluating thermal-hydraulic characteristics. In this study, the system design requirements were established in accordance with the international standard ISO 16646:2024 and the operational specifications of the device. This involved calculating the system airflow capacity and proposing a preliminary process design scheme for the negative pressure ventilation system. A thermal-hydraulic computational model for the initial system configuration was developed using the fluid simulation software AFT Arrow. Steady-state simulations were conducted to predict the thermal-hydraulic behavior of the pipeline network under maximum ventilation load conditions, enabling the determination of critical equipment selection parameters. The findings of this study will lay the groundwork for subsequent research on negative pressure ventilation systems in compact fusion energy applications, providing essential technical insights for optimizing system performance and ensuring compliance with radiological safety standards.</p>