For a flexible data switching, a hybrid switching network of packet switching and circuit switching has been studied and implemented using the CCITT recommendations. For the part of packet switching in this network, the packet-level protocols and PAD (packet assembly and disassembly) function are designed and implemented. After a general discussion on the structure of the network, the packet-level subsystems and software structure are investigated. Data transfer algorithm between two switching processors and the data buffering method are designed. Also a single routing method is implemented for the network. The system performance including call response time, waiting occurrence in buffer and routing function is discussed in detail.