A method and system for determining a QoS of a WLAN service in a backhaul network are disclosed. The method includes: distinguishing whether a WLAN service or a WLAN instruction is to be returned, if the WLAN service is to be returned, recording a QoS of the WLAN service in a WLAN; and according to a preset mapping relation between the QoS of the WLAN service in the WLAN and a QoS of an ordinary service in the backhaul network, obtaining a QoS corresponding to a WLAN backhaul service in the backhaul network.