Optimizing the eye diagram performance of the transmitting optical signal and the sensitivity of the receiving signal ofthe optical module is the key to improving the transmission link budget of the high-speed optical network unit（ONU） optical module. A 25G ONU optical module with high speed performance is designed. First, the processing skills of high-speed signal lineimpedance discontinuity and the mechanism of the impact of printed circuit board（PCB） punching process design on the bandwidthperformance of transmission signal line are thoroughly studied. Then, the reference stack structure is adjusted and the via processmode is optimized. Finally, the high-speed signal simulation and analysis are carried out. The test results show that the designedmodule not only fully meets the performance requirements of the transmitting eye diagram and receiving sensitivity, but also has aperformance margin far exceeding the IEEE802.3ca protocol standard.