An efficient extraction method, called negative-pressure cavitation extraction (NPCE), was investigated for the extraction of the two main flavonoids biochanin A and genistein from Dalbergia odorifera T. Chen leaves and their antioxidant activity was evaluated. The extraction conditions were firstly optimized by single factor experiments. Then, a Box-Behnken design (BBD) combined with response surface methodology was used to study the most effective factors. Optimal conditions were extraction time 20 min, three extraction cycles, negative pressure -0.05 MPa, ethanol concentration 66% and liquid/solid ratio 24:1 mL g(-1). Under optimized conditions, the yields of biochanin A and genistein were 1.583 and 0.933 mg g(-1) DW, respectively. Furthermore, the antioxidant activity of NPCE extract was assessed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay. NPCE extracts possessed notable concentration-dependent antioxidant activity with IC(50) values of 0.194 mg/mL. The results demonstrated that NPCE would be lower energy consumption, higher efficiency and could be an alternative method for natural compounds extraction. (C) 2011 Elsevier B.V. All rights reserved.