Marine stable nitrogen isotope containing much key biogeochemical information, is an important way in identifying marine nitrogen sources and understanding the marine nitrogen cycles. These isotopic signals can be preserved in marine sediments and used to trace the marine biogeochemical cycles and environment changes during geological history. Studies in recent decades have illustrated the key role of nitrogen fixation and denitrification. Because of the spatiotemporal variability and the complexity of ocean processes and nitrogen sources in the marine environment, we need to combine the modern observations with geological records, integrate oceanography, biology, and geology, and consider the hydrological environment, geological processes and climate changes, to understand the coupling between the ocean nitrogen cycle， climate and environmental changes.