Disclosed in an embodiment of the present invention are an inter-network service shunting method and device, the method comprising: controlling a user equipment (UE) to transmit an ISRP request to an ANDSF unit by a network side through a capability negotiation between the ANDSF unit and the UE; accessing a non-3GPP network by utilizing an instruction for accessing a non-3GPP network generated by the ANDSF unit instruction on the basis of the ISRP request; upon simultaneous connection to the 3GPP network and the non-3GPP network by a UE, and according to an ISRP shunting strategy issued by the ANDSF unit on the basis of the ISRP request, instructing the UE on which services to reside in the 3GPP network and which services to reside in the non-3GPP network. The above process enables independent execution of an ISRP shunting strategy to shunt services in the 3GPP, thus enabling a network side to control a UE to initiate an ISRP process through capability negotiation, thereby saving network resources during service shunting.