Abstract: Tristructural-isotropic (TRISO) coated fuel particles in high temperature gas-cooled reactor (HTGR) were fabricated using fluidized bed chemical vapor deposition (FB-CVD) method. It is found that the pressure of the CVD system named reaction pressure is a key parameter which can influence the properties of the coated fuel particle by experimental study. In this work, the variation of the reaction pressure in the coating process and its influence on the microstructure and density of the coating layers were investigated. To control the reaction pressure, the concept of whole production line pressure assessment was proposed. Pressure analysis and balance were obtained by monitoring some pressure points in the production line. Based on the system pressure assessment, the pressure optimization was obtained which could keep the pressure balance of the whole production line and keep the stability of production process. It can be indicated that the pressure analysis is an effective method to assess the production line, which can be used to production line troubleshooting, hierarchical interlocking design and system optimization in the future.