A method for controlling data transmission and reception and an application system thereof are provided. In the method, the peer-to-peer communication system is initialized to set each communication unit in the peer-to-peer communication system to be in a data receiving state. A communication host controls, according to a communication status of the peer-to-peer communication system, a controlled electrical connection path between the communication host and a communication interface to the communication transmission path, to work in a mode allowing data transmission from the communication slave to a communication host side of the controlled electrical connection path, or a mode allowing data transmission from the communication host side of the controlled electrical connection path to the communication slave.