Abstract:13-1,4-endoxylanase from Triehoderma pseudokonigi Rifai has been purified by anion-exchange chromatography on DEAE-Sephadex A50, DEAE-Sepharose CL-6B and mono Q. The endoxylanase was shown to be homogeneous by Native-PAGE and SDS-PAGE. This endoxylanase is a single-peptide chain protein with a molecular weight estimated as 66 kD. The endoxylanase was purified by 10-fold with a specific activity of 15.87 U·mg－1 Optimum endoxylanase activity was obtained when the enzyme was incubated at pH 4.5, 55 ℃ with a Km of 20 mg/mL and Vmax of 3.3 μmol·min－1·mg－1. Hg2 + and Cu2 + have a strong inhibition while Fe2 + and Mn2 + have a increasing effect on the enzymatic reaction rate.