Abstract: Wireless communication network is one of the key technologies for railway train dispatch and train operation control services. The existing GSM-R narrow band network is no longer able to meet the ever-increasingly diverse needs of railway operation in terms of communication capacity and performance. With the transition of railway wireless communication technology from GSM-R circuit switching to GPRS packet switching, TCP/IP protocols have been included in the specifications of the train control system, ETCS and CTCS, to carry reliable transmission services. Referring to relevant domestic and foreign specifications, this article expounds the peer-to-peer communication layer structure and train ground communication process of GPRS packet switching communication network. A design of the packet switching communication software for the on-board equipment of the train control system based on the open source protocol stack lwIP is proposed, which has a layered architecture and modular design and can be upgraded by simply modifying the circuit switching communication part of the original application software and security mechanism of the train control system without any other modification to achieve seamless migration of train control services to GPRS packet switching network. The communication software has been successfully ported to the onboard hardware platforms of multiple domestic automatic train operation (ATO) systems and automatic train protection (ATP) systems with domestic operating systems.