Abstract: Objective: to explore the relationship between nitric oxide( ·NO) and S-nitrosothiols. Methods: spectrophotometer, capillary electrophoresis and chemiluminescence methods have been used to study the oxidative process of ·NO and the stability of S-nitrosothiols. Results: authentic ·NO will be quickly oxidized by oxygen and mainly forming nitrite, which is very stable in neutral pH condition. When the system pH decreased, a very fast formation of S-nitrosothiols has been determined. S-nitrosothiols also could be spontaneously releasing ·NO, which is stimulated by oxygen free radicals. Conclusion: it is further provide the evidence to support the hypothesis that EDRF is nitroso complexes.