Aiming at the shortage of XML and JSON data structure in the aspect of data communication, a data transmission protocol is designed to ues the data communication between gateway and data platform. It takes full advantage of the Protobuf that is portable and uses the binary data stream to transmit data. The protocol encapsulates data transmitted in Protobuf format in a message and builds a data transmission channel using the application layer protocol defined and the confirmation mechanism designed. It also introduces the serialization method of data to achieve the transmission of message. The test results show that the data transmission protocol achieve data transmission efficiently and reliably between the gateway and data platform.