The invention provides a consistency message transmission method and system, a bus interface controller and a chip. A first bus interface controller receives a first consistency message in a first cache consistency sub-domain; the first bus interface controller belongs to the first cache consistency sub-domain; the first consistency message carries a message type and a destination address; the first bus interface controller determines a packaging format according to the message type of the first consistency message and preset packaging related information, processes the first consistency message into a first packaging message, and sends the first packaging message to a second bus interface controller belonging to a second cache consistency sub-domain through a bus interface according to the destination address of the first consistency message; and the first consistency message in the first cache consistency sub-domain is sent by a processor core in the first cache consistency sub-domain or a last-level cache. According to the transmission method provided by the invention, the consistency message between the sub-domains can be transmitted through the bus interface.