A path determining method, applied to a hybrid network comprising one controller for implementing a control function, wherein the hybrid network further comprises a first network and a second network of different network types, the second network is an optical network, and the method comprises: obtaining, by the controller, a path determining requirement, wherein the path determining requirement is used to request to determine a data transmission path from a first network device to a second network device that comprises a transmission path part in the first network and a transmission path part in the second network, the path determining requirement comprises an identifier of the first network device and an identifier of the second network device, and both the first network device and the second network device are network devices in the first network; obtaining, by the controller, network topology information of the first network from a network device in the first network and network topology information of the second network from a network device in the second network according to a same control channel protocol, wherein the control channel protocol is a Path Computation Element Communication Protocol, PCEP; calculating, by the controller, a path computation result based on the identifier of the first network device, the identifier of the second network device, the network topology information of the first network, and the network topology information of the second network, wherein the path computation result comprises a computation result of the transmission path part of the data transmission path in the first network and a computation result of the transmission path part of the data transmission path in the second network; and sending, by the controller, the path computation result to the first network device. obtaining, by the controller, a path determining requirement, wherein the path determining requirement is used to request to determine a data transmission path from a first network device to a second network device that comprises a transmission path part in the first network and a transmission path part in the second network, the path determining requirement comprises an identifier of the first network device and an identifier of the second network device, and both the first network device and the second network device are network devices in the first network; obtaining, by the controller, network topology information of the first network from a network device in the first network and network topology information of the second network from a network device in the second network according to a same control channel protocol, wherein the control channel protocol is a Path Computation Element Communication Protocol, PCEP; calculating, by the controller, a path computation result based on the identifier of the first network device, the identifier of the second network device, the network topology information of the first network, and the network topology information of the second network, wherein the path computation result comprises a computation result of the transmission path part of the data transmission path in the first network and a computation result of the transmission path part of the data transmission path in the second network; and sending, by the controller, the path computation result to the first network device.