By exploring the discussions about the nine-needle in Neijing and making a summary of its number shapes and ap-plications,we find that the nine-needle theory has the feature of concerning morphological structure which is the same as new acupuncture tools and therapies today and very different from "mind-balance" of filiform needle.However,we consider that the nine-needle theory which possesses the feature of"structure-needling" should but did not have enough influence on the de-velopment of acupuncture.So we call for paying more academic attention to "physics" during the development of modern acu-puncture and making acupuncture more practical.