A data transmission method, device, and system relate to the field of communications technologies, and provide a more flexible network topology and reduce network overheads. The method includes sending, by a first wearable device, a first broadcast message to a second wearable device, determining whether the second wearable device supports processing of service data of the first wearable device when the first wearable device obtains by listening, a second broadcast message from the second wearable device, and when the first wearable device determines that the second wearable device supports processing of the service data, establishing a connection to the second wearable device, and sending the service data in an allocated receive or transmit timeslot to the second wearable device.