Abstract: Tea seed shell(TSS) were fermented with Aspergillus niger, Bacillus subtilis and Saccharomyces cerevisiae, by using immobilized cell fermentation technology, and the water extract of the fermentation product was prepared. The analysis showed that compared with the unfermented water extract, the content of main antioxidant substances in the fermented extract of S. cerevisiae (FETSS-3) increased significantly, the content of polysaccharides, polyphenols and saponins increased to 9.19, 9.59 and 4.67 times respectively. Its antioxidant activity was investigated by biochemical level, cellular level and enzyme activity level, and its skin safety was confirmed by patch test. The results showed that in the concentration range of 0.1-0.4 g/L and 0.5-2.0 g/L, ABTS and·OH radical scavenging activities of FETSS-3 were significantly superior to those of V_C(P < 0.01; P < 0.01); In the concentration range of 0.2-1.2 g/L, its IC₅₀ was only 21.98% of that of V_E, and its inhibitory activity was significantly higher than that of V_E(P < 0.01). In the concentration range of 20-120 mg/L, FETSS-3 could significantly reduce the level of oxidative damage stress of human skin fibroblasts(HSF) induced by H₂O₂(P < 0.01). In vitro enzyme activity experiments showed that FETSS-3(120 mg/L) could significantly improve the activity ofcatalase(CAT), superoxide dismutase(SOD) and glutathione peroxidase(GSH-PX) in HSF cells after oxidative stress injury(P < 0.05; P < 0.01; P < 0.01). The human body patch experiment showed that the FETSS-3 had no risk of skin allergy.