Grazing exclusion is an effective measure to enhance carbon sequestration in degraded grassland ecosystems, playing a crucial role in the natural restoration of grassland productivity and ecosystem stability. By excluding livestock grazing, grazing exclusion can restore vegetation biomass and increase soil organic carbon (SOC) content. However, the effectiveness of grazing exclusion is influenced by management practices, climatic factors, grassland types, and soil conditions. This paper summarizes the current research on the restoration effects of SOC under grazing exclusion conditions, mainly focusing on organic carbon input and output processes. It is found that there is currently limited research on the stability of soil organic carbon, especially on the more stable and less decomposable organic carbon components derived from plants and microorganisms, which leads to a lack of comprehensive and systematic understanding of SOC responses and mechanisms to grazing exclusion. We further proposed future research directions on SOC dynamics under grazing exclusion: (1) enhancing the study of different SOC components under grazing exclusion to explain the variations in SOC responses to grazing exclusion in different climatic regions; (2) investigating the relationship between soil microbial functional groups and SOC input and decomposition, to reveal the mechanisms and patterns of microbial regulation of SOC responses to grazing exclusion; (3) clarifying the changes in underground carbon pools over different periods during long-term enclosure, with enhanced periodic and long-term observations in experiments to more accurately elucidate the impact of grazing exclusion on SOC turnover, and to scientifically assess the appropriate duration of grazing exclusion for grasslands; (4) strengthening the coupling research of grazing exclusion with global climate change factors, as comprehensive analyses of the climatic drivers of SOC dynamics in different grassland types under grazing exclusion, particularly in alpine grasslands like the Qinghai-Tibet Plateau, are still lacking.