Embodiments of the present invention provide a method and apparatuses for monitoring a system bus. The method includes: performing, by a monitoring apparatus, real-time monitoring on a corresponding system bus, and when detecting that a command is transmitted through the system bus, obtaining command information; determining, according to the command information, whether a command transmission exception occurs in the system bus; if no command transmission exception occurs in the system bus, when detecting that data corresponding to the command is transmitted through the system bus, determining, according to the data and the amount of the data, whether a command exception occurs in the system bus; and when detecting that a response message corresponding to the command is transmitted through the system bus, obtaining a command wait time of the command, and determining, according to the command wait time, whether a timeout exception occurs in the system bus.