[Objective] The preponderant strain was isolated from brick tea. Studies on its physiological and biochemical characteristics in cultivation, which provide the basis for the actual production of brick tea fermentation. [Methods] Strains were obtained from brick tea by dilution plate method in PDA. Based on common fungus fermentation method, the culture conditions was selected by the single factor method, and than culturing conditions were optimized using response surface methodology. Contents of reducing sugar, polyphenols, enzyme activity and antioxidant capacity from fermented liquid were determined. [Results] The preponderant strain was identified as Eurotium cristatum by the morphology and ITS sequence analysis. The optimization culturing conditions were: 187 r/min, 10 d, 28 °C. And then yield of biomass was 21.52 g/L. The four kinds of extracellular enzyme activity reached the maximum value at 10th days, meanwhile extracellular polyphenol (EP) 0.588 g GAE (gallic acid)/mL at 9th day. The fermentation liquid of E. cristatum showed antioxidant activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical. The scavenging effects towards DPPH and hydroxyl radical were 90% and 94%, respectively. [Conclusion] Fungal strain MJAU EC021 was E. cristatum. And then the fermentation liquid had good antioxidant capacity, which is a potential antioxidant additive.