Abstract: 【Objective】The contents of different forms of phenols of Cinnamon cassia and the effects of different forms of phenolic extracts on non-alcoholic fatty liver disease(NAFLD)were studied in order to provide a theoretical basis for the processing of cinnamon resources and the development of functional foods of cinnamon.【Method】The contents of phenols and flavonoids in cinnamon were analyzed by the Folin phenol method and the sodium borohydride/chloranil based assay(SBC),respectively. HepG2 cells induced by sodium oleate and palmitic acid(2:1)were used as an in vitro model to analyze the regulation effects of different concentrations of free or bound phenolic extracts of C. cassia on the formation of intracellular lipid droplets. The change of triglyceride(TG)content of different groups was also determined. Compared with the bound phenolic extract,the free polyphenol extract of cinnamon showed a better effect on steatosis. Furthermore,mice fed on a high sugar and high fat diet in combination with streptozotocin(STZ)was used as to model the in vivo effects of the phenolic extracts on serum and liver lipids.【Result】The results suggested that polyphenols(55.99±0.45 mg GAE/g)existed in cinnamon extracts mainly in free form. Notably,some bound polyphenols(3.21±0.12 mg GAE/g) were also detected. The flavonoids(46.49±4.75 mg CE/g)were the main component of cinnamon polyphenols. The free phenolic extract of the Yunye cultivar of cinnamon can effectively reduce the TG level in vitro. The extracts of medium and high dose groups significantly decreased the TG level by 17.07% and 26.83% relative to that of the model group,respectively(P<0.05,the same below). There was no significant difference in intracellular TG level between the model group and the bound phenol extract group(P>0.05). The results of animal experiments showed that the contents of TG,total cholesterol(TC)and low-density lipoprotein cholesterol(LDL-C)in the serum of mice decreased significantly after the intervention of high dose free phenol extract. High dose cinnamon free phenol extract also significantly reduced the contents of TG and FFA in the liver of mice,which decreased by 42.21% and 22.22%,respectively. The results of LC-MS/MS showed that procyanidins C1,B2,A2,B3 and B₁ may be the main flavonoid compounds of the cinnamon free phenolic extract.【Conclusion】These results reveal that cinnamon free phenolic extract may have a good effect on NAFLD,and procyanidins may be the main compounds effective against the steatosis of liver cells