The present disclosure relates to integrated access and backhaul (IAB) node dual connectivity setup methods and communication apparatus. In one example method, a first IAB node sets up a first F1 interface with a primary donor node of the first IAB node. The first IAB node obtains an internet protocol (IP) address anchored at a secondary donor node connected to the first IAB node and/or configuration information of a serving cell, of the first IAB node, belonging to the secondary donor node. The first IAB node sends, to the secondary donor node, a request for setting up a second F1 interface with the secondary donor node, where the request includes the configuration information of the serving cell, of the first IAB node, belonging to the secondary donor node.