The embodiments of the present disclosure disclose a small data transmission method and a related device and system. The method may include: broadcasting, by a base station, a paging message, where the paging message carries UE identifiers of a plurality of to-be-paged user equipment UE and small data sent to at least one of the to-be-paged UEs, and the small data is data whose data volume is less than a preset data volume threshold. In the present disclosure, small data may be sent to to-be-paged UE while the base station pages the UE, to reduce signaling and time overheads for sending the small data and improving communication efficiency.