ObjectiveTo study the influencing factors for hollow process challenge devices (PCDs) in steam sterilization. MethodsTwo hollow PCDs were tested in a vacuum steam sterilizer (XHJCA BD resistance comprehensive detector) under different vacuum depths and vacuum rates. ResultsTo the same type of PCD, the deeper the vacuum depth, the less the pulse times; To the same vacuum depth, long  hollow PCD was more difficult to pass than short hollow PCD. When the vacuum rate was 50~100 kpa/min, the long hollow PCD was more difficult to pass than the short hollow PCD. ConclusionThe vacuum depth and vacuum rate of steam sterilizer can influence the monitoring result and the sterilization quality.