The present application relates to the field of Internet of Things technologies, and in particular, to a message queuing telemetry transport (MQTT) data transmission method, apparatus, and system, so as to provide a solution for simply implementing a security function of the MQTT protocol. A data obtaining relationship between an MQTT publishing device and an MQTT subscribing device is verified before MQTT data publishing, and data sending is controlled by using an SDP gateway. Therefore, security of the MQTT data publishing can be effectively ensured. Moreover, protocol modification is relatively little, and implementation is simple.