The present disclosure discloses a data transmission method for an edge MBMS service and a related device. The method includes providing an MBMS service data transmission system that includes a central BM-SC located on a core network and an edge BM-SC and an MBMS GW that are located on a network edge; creating, by the central BM-SC, a control-plane bearer context; sending a session start request to the edge BM-SC, so that the edge BM-SC creates a user-plane bearer context; receiving a session start response sent by the edge BM-SC; and delivering a service key to the edge BM-SC, so that the edge BM-SC encrypts data of the edge MBMS service by using the service key and sends data to UE via the MBMS GW.