A signal transmission method, comprising: receiving (S104, S204, S304, S404), by a first device (103, 300, 500, 600), resource configuration information for a reference signal sent by a second device (103, 300, 500, 600), wherein the reference signal is used to measure interference between a first link and a second link, the first link is an access link between the first device (103, 300, 500, 600) and a fourth device that is a terminal, the second link is a backhaul link between the second device (103, 300, 500, 600) and a third device (101, 400), and the first device (103, 300, 500, 600) and the second device (103, 300, 500, 600) are relay nodes between the third device (101, 400) and the fourth device; and sending or receiving (S106, S206, S306, S406), by the first device (103, 300, 500, 600), the reference signal on a reference signal resource indicated by the resource configuration information for the reference signal, wherein the method further comprises: sending, by the first device (103, 300, 500, 600), first reporting information to the second device (103, 300, 500, 600), wherein the first reporting information is used to indicate whether the first device (103, 300, 500, 600) has a multi-link beam correspondence capability; the multi-link beam correspondence capability comprises at least one of the following: a capability of the first device (103, 300, 500, 600) to send or receive, on the first link and a third link, reference signals on antenna ports having a quasi co-location, QCL relationship; or a capability of the first device (103, 300, 500, 600) to send or receive reference signals on the first link and a third link by using a same beam or a same spatial filter; and a backhaul link between the second device (103, 300, 500, 600) and the first device (103, 300, 500, 600) is the third link. receiving (S104, S204, S304, S404), by a first device (103, 300, 500, 600), resource configuration information for a reference signal sent by a second device (103, 300, 500, 600), wherein the reference signal is used to measure interference between a first link and a second link, the first link is an access link between the first device (103, 300, 500, 600) and a fourth device that is a terminal, the second link is a backhaul link between the second device (103, 300, 500, 600) and a third device (101, 400), and the first device (103, 300, 500, 600) and the second device (103, 300, 500, 600) are relay nodes between the third device (101, 400) and the fourth device; and sending or receiving (S106, S206, S306, S406), by the first device (103, 300, 500, 600), the reference signal on a reference signal resource indicated by the resource configuration information for the reference signal, wherein the method further comprises: sending, by the first device (103, 300, 500, 600), first reporting information to the second device (103, 300, 500, 600), wherein the first reporting information is used to indicate whether the first device (103, 300, 500, 600) has a multi-link beam correspondence capability; the multi-link beam correspondence capability comprises at least one of the following: a capability of the first device (103, 300, 500, 600) to send or receive, on the first link and a third link, reference signals on antenna ports having a quasi co-location, QCL relationship; or a capability of the first device (103, 300, 500, 600) to send or receive reference signals on the first link and a third link by using a same beam or a same spatial filter; and a backhaul link between the second device (103, 300, 500, 600) and the first device (103, 300, 500, 600) is the third link. a capability of the first device (103, 300, 500, 600) to send or receive, on the first link and a third link, reference signals on antenna ports having a quasi co-location, QCL relationship; or a capability of the first device (103, 300, 500, 600) to send or receive reference signals on the first link and a third link by using a same beam or a same spatial filter; and a backhaul link between the second device (103, 300, 500, 600) and the first device (103, 300, 500, 600) is the third link.