Ultrasonic technology was used to extract chlorogenic acid from the leaves and barks of Eucommia ulmoides Oliv.and establish HPLC-PAD method for determining the content of chlorogenic acid.The result showed that the content of chlorogenic acid in the leaves of E.ulmoides was higher than that in the barks.The method was simple and accurate with wide linear range and could be used to evaluate the quality of medicinal materials that contained chlorogenic acid.