High salinity is considered to be one of the major abiotic stress factors that are detrimental to algal growth and development. In order to protect itself from high salinity, U.prolifera can sense salinity stress and trigger signaling pathways to activate relevant physiological mechanisms, and can also release germ cells to form new individuals. However, the molecular mechanisms involved in the level of protein s -nitrosylation in response to salt stress in macroalgae remain largely unknown.In this study, we performed quantitative proteomics analysis of protein modifications and identified a total of 1,620 proteins modified by S-nitrosylation in U.prolifera, in which a variety of antioxidant enzymes, including APX, CAT, and GR were up-regulated at the level of S-nitrosylation in response to salt stress. Further in vivo and in vitro validation results indicated that protein s-nitrosylation plays a positive role in enhancing antioxidant enzyme activities under short-term salt stress in U.prolifera. In addition, we explored the level of s-nitrosylation of key proteins associated with spore formation in U.prolifera, which will further improve our understanding of the molecular mechanisms of NO signaling and provide preliminary insights into the regulatory role of NO in U.prolifera spore formation.