Front-end electronic system is an important component of PET (Positron Emission Tomography), which accomplishes the disposal and real-time high speed transmission of detected data. Netcom's Gigabit module is important for the front-end electronic systems and the follow-up data transmission system. In order to improve the data transmission speed of the system, this paper has suggested a design using FPGA to realize the network transmission. A detailed description and analysis of network agreement used in PET data transmission network is given in the paper. And combined with the network transmission in PET, the agreement that meets the transmission hardware features is proposed. In addition, the hardware design and implementation of gigabit transmission system is further studied. The design of FPGA-based Gigabit network transmission system in PET is completed, and therefore the high-speed network data transmission for the front-end electronics system is realized.