Abstract: With the wide use of vehicle compressed natural gas cylinders, the on-line inspection technology of vehicle compressed natural gas cylinders need to be researched. In this paper, the on-line inspection testing of vehicle compressed natural gas cylinders containing artificial simulation defects was carried out through the acoustic emission technology, the inspection results were compared to the standard of GB 19533—2004 Periodic inspection and evaluation of vehicle compressed natural gas cylinders, which provided the evidence for the popularization and application of acoustic emission on-line inspection of vehicle compressed natural gas cylinders of our country.