Embodiments of this application provide a data sending method, apparatus, and system, and relate to the communications field, so that an SN change in dual connectivity does not affect performance of a network in which an MN is located. The data sending method specifically includes: determining, by a source node device, whether direct data forwarding is supported between the source node device and a destination node device; and sending, by the source node device, a first message including a first indication to a first node device, where the first indication is used to indicate whether the direct data forwarding is supported between the source node device and the destination node device. This application is used for data sending.