The invention relates to the field of communication technology, and discloses a data transmission method, device and system. A data transmission method for signal equipment comprises the following steps: generating a first encapsulated data packet, wherein the first encapsulated data packet includes a first network address and a first port number of the signal equipment, a second network address and a second port number of target signal equipment, and first data; and sending the first encapsulated data packet to communication equipment, wherein the communication equipment can send the first encapsulated data packet to target communication equipment corresponding to the target signal equipment according to the mapping relationship between the second network address stored in a DNS domain name server and the corresponding target communication equipment. According to the data transmission method, device and system disclosed by the invention, the high-speed and reliable two-way data transmission between the signal equipment can be achieved.