Objective:To construct a high-flux screening procedure by on-line free radical scavenging activity method of phytochemicals, and create a new evaluation system of antioxidant activity of natural plant materials. Methods:A HPLC system with two detectors and flow injection techniques was employed. An organic free radicals DPPH was induced on-line HPLC-DPPH and reaction with the single phytochemical components isolated by HPLC. To optimize reactive conditions including flow rate and the size of reaction coil, and detect the DPPH signals before and after reaction. Results:A new on-line HPLC-DPPH method was established for a high-flux screening of several free radical scavenging components exampled as Tea polyphenols and Salvianolic acids. The reaction coil of PEEK was 10 m length and inner diameter 0.254 mm, the concentration and flow velocity of DPPH was 1.0 × 10-5mol/L and 0.7~0.8 ml/min, respectively. Conclusion:The PHLC-DPPH flow injection hyphenated technique could realize high-flux screening analysis for antioxidant of phytochemicals.