The present disclosure relates to a method of transmitting a packet by an Integrated Access and Backhaul (IAB) node in a wireless communication system. In particular, the method includes the steps of: receiving, from a first node, an indication indicating that a congestion problem occurs between the first node and a second node; if the packet is to be transmitted to other node via the first node, transmitting the packet to the first node; and if the packet is to be transmitted to the second node via the first node, transmitting the packet to a third node.