An ultra-high-speed (UHS) tube system, also known as a super-speed tube system, enables vehicles transport at ultra-high speed by reducing the air resistance. Airtightness is one of the most important requirements of the system as the system must maintain reduced pressure for a certain period of time. This study develops a predictive model for evaluation of the airtightness performance of a concrete UHS tube with cracks. A differential equation is derived for description of the internal pressure change with time by applying the air leakage model. A sensitivity analysis is then performed for identification of crucial factors that affect the airtightness of the system. The analysis results indicate that the airtightness of the system is highly dependent on the status of the cracks, especially the average width. It is expected that the model developed in this study can be effectively used for establishment of the crack criteria associated with the airtightness of a UHS tube system.