This invention to a process of extracting and purifying biologically effective ingredients from combined medicinal plants and their plant extract composition and more particularly, to a process for effective extracting and purifying the biologically effective ingredients by mixing Clematis Radix , Trichosanthes root and Prunella Herba in a certain ratio, being useful for alleviating acute/chronic inflammation and also for inhibiting platelet/whole blood aggregation, abnormally proliferated immunocytes (e.g., B-lymphocyte, T-lymphocyte), inflammation-inducing enzymes (5-Lipoxygenase, Cyclooxygenase-I, Cyclooxygenase-II) and also scavenging activity on toxic active oxygen species when compared to a single plant extracts, toghter with their extract composition, which may be effectively used as an anti-inflammatory agent with analgesic effects, rheumatoid arthritis drug and agents for improving peripheral blood circulation.