In order to achieve efficient extraction of active ingredients in blackberries， this study was conducted to investigate the effect of fermentation treatment on the components of blackberry extracts and its protective effect on tert-butyl hydroperoxide-induced oxidative stress damage in human umbilical vein endothelial cells(HUVEC). Compared with unfermented blackberry extracts(BH)， the content of total sugar， soluble protein， vitamin C in fermented blackberry extracts(BF) remained basically unchanged， and the content of total phenols， anthocyanins and ellagic acid increased by 43.4%， 41.7% and 44.4%， respectively. In terms of antioxidant capacity， BF protected HUVEC cells from oxidative damage by reducing the content of reactive oxygen species， lactate dehydrogenase and malondialdehyde， and increasing the total antioxidant capacity and superoxide dismutase activity， and the effect of BF was superior to that of BH. The results showed that the fermentation process adopted in this study can effectively promote the dissolution of active ingredients in blackberry and improve its antioxidant capacity， provide new ideas for the development of blackberry functional food.