A method for switching of multi-carrier and device are provided. The method comprises: receiving a message sent from a source RAN node corresponding to a first link and comprising information of a second link; according to the information of the second link, establishing a connection between a target RAN node corresponding to the first link and an RAN node corresponding to the second link, so as to perform data transmission. The first link is a link in a first Radio Access Technology (RAT) network, and the second link is a link in a second RAT network. Embodiments of the present invention can ensure the continuity of the throughput of data transmission during switching under aggregation of multiple RAT carriers.