Extraction of active constituents is the key to economic exploitation of herbal drugs in which appropriate use of experimental design can be employed. This paper used even-plan design to assess parameters for optimum extraction of ursolic acid and oleanolic acid in Fructus crataegi. In this approach, three factors, namely solvent concentration, extraction time and solvent volume, were evaluated according to even-plan design, in which several factors are usually simultaneously varied. As a result the number of experiments as well as time, was reduced as compared with the univariate approach and other designs. It was demonstrated that with even-plan design, useful information on extraction parameters can be obtained for the extraction of herbal drugs and could therefore be successfully applied to screen extraction conditions for herbal drugs. Extraction of active constituents is the key to economic exploitation of herbal drugs in which appropriate use of experimental design can be employed. This paper used even-plan design to assess parameters for optimum extraction of ursolic acid and oleanolic acid in Fructus crataegi. In this approach , three factors, comprising solvent concentration, extraction time and solvent volume, were evaluated according to even-plan design, in which several factors are usually synchronized varied. univariate approach and other designs. It was said that with even-plan design, useful information on extraction parameters can be for the extraction of herbal drugs and could therefore be successfully applied to screen extraction conditions for herbal drugs.