The invention relates to a safety defending system and method of information system or equipment, it possesses several client machines which are used to access several information systems or equipment; access control unit which is set between client machine and said information system or equipment to make the client machine log on information system or equipment via digital certificate; authentication authorization unit which matches with the access control unit to identify user which logs on via digital certificate, and obtains corresponding access popedom list; account management unit whichstores the digital certificate principal part mark and mapping of account and password which are used to access information system or equipment, and is used to realize the association of digital certificate principal part and information system or account and password; client machine matches with said access control unit to pick up account and password information of information system or equipment from access popedom list, the logging course of information system or equipment is accomplished.