The packet segment offloading and sending mechanism was proposed and the prototype system was implemented. This mechanism, based on the multi-core packet processing system with lightweight input/output, was aimed to reduce the cost of large packet segmentation, copy overhead, hardware and software complexity. It offloaded the complex parts of hardware implementation to the drive including packet segmentation, packet head encapsulation. It reduced the whole data copy cost to the copy cost of the new packets header, combined the chain direct memory access technology to provide an effective solution of packet forwarding on the multicore system. The packet sending performance based on domestic general multi-core and field-programmable gate array platform was tested. The experimental data shows that the packet segment offloading and sending mechanism can significantly enhance the performance, and effectively solve the problem of the large packet sending on the multicore network processing system.