Objective: To optimize purification process of bibenzyl compounds from Dendrobium aurantiacum with macroporous resin and investigate its antioxidant ability before and after being purified. Method: With static adsorption capacity and elution ratio as indexes

five types of macroporous resin(X-5

HPD-300

D-101

AB-8 and S-8) were used to purify bibenzyl compounds by static adsorption-elution test.Single factor tests were adopted to investigate effects of the concentration of sample solution

the largest sample volume

ethanol concentration and other factors on purification process of bibenzyl compounds

and antioxidant ability of bibenzyl compounds was determined. Result: HPD-300 type of macroporous resin was selected

its optimum purification process was as follows:the concentration of sample solution 9.04 g·L-1

the largest sample volume of 1.25 BV

sampling flow rate at 0.5 mL·min-1

separately eluted with 5 BV water and 70% ethanol at flow rate of 1.0 mL·min-1. Under these conditions

purity of bibenzyl compounds could reach 67.07%

which increased 4.25 times by compared with unpurified.IC50 of refined and crude bibenzyl compounds for superoxide anion radical were 0.408 and 0.985 g·L-1

but they were 7.856 and 7.827 g·L-1 for hydroxyl radical

respectively. Conclusion: HPD-300 type of macroporous resin had an excellent purification effect for bibenzyl compounds of D. aurantiacum

its purity and antioxidant ability were improved remarkably.