Apnea testing (AT) is one of the key steps for brain death (BD) diagnosis and confirmation. However, the completion rate of AT is not well in China. The aim of this study was to investigate the completion rates of the AT during BD determination in China and analyze the determinant factors. We reviewed and analyzed potential BD patients registered in our database from 2013 to 2019. The patients were divided into those with completed and aborted AT. Preconditions and organ function status were compared between the two groups. A total of 1,531 (1,301 adults and 230 pediatrics) cases of potential BD were extracted, and BD determination was performed 2,185 and 377 times in adults and pediatrics respectively. The nonperformance and aborted rates of AT were 12.2% and 34.5% in adults, and 11.7% and 44.4% in pediatrics respectively. Compared with the completed group, the aborted group had a lower PaO2, systolic blood pressure, PaO2/FiO2 ratios, and higher alveolar-arterial (A-a) gradient both in adults and pediatrics, and higher PaCO2 and higher heart rates in adults. PaO2 and A-a gradient had higher predictive efficacy for AT completion in both adults and pediatrics. The implementation and completion rates of AT are not ideal in China. PaO2 and A-a gradient are important factors for the successful completion of AT and should be optimized before AT. Copyright © 2021 by the American Society for Artificial Internal Organs.