To investigate change of nitric oxide（NO）/NO synthase（NOS）in Qi-blood stagnation of rats. Methods:Wistar rats were randomized to four groups: normal control group， model group， low concentration group， and high concentration group. The Qi-blood stagnation model was established by complex pathogens. The content of NO in plasma and liver tissues of rats was measured by spectrophotometric. RT-PCR was used to analyze liver tissues NOS mRNA expression. Results:The plasma NO of model group［（0.52±0.33）μmol/L］ decreased significantly compared with normal control group［（2.77±1.73）μmol/L］（P<0.01）.The plasma NO of treatment group［（2.37±0.53）μmol/L］ increased significantly compared with model group［（0.52±0.33）μmol/L］（P<0.01）.The NO in liver tissues of model group［（0.52±0.24）μmol/mg］ decreased significantly compared with normal control group［（5.87±1.72）μmol/mg］（P<0.01）.The NO in liver tissues of treatment group［（3.72±1.53）μmol/mg］ increased significantly compared with model group［（0.52±0.24）μmol/mg］（P<0.01）.The expression of NOS in liver tissues NOS mRNA expression in model group decreased significantly compared with normal control group (P<0.01). The expression of NOS in liver tissues NOS mRNA expression in low concentration increased significantly compared with model group (P<0.05). Conclusion:Nitric oxide（NO）/NO synthase（NOS）was down-regulated in Qi-blood stagnation rats.