Acupoint catgut-embedding (ACE) therapy is a type of acupuncture surgery that combines concepts of traditional Chinese medicine with modern medical instruments. The therapy involves using a hypodermic needle and an acupuncture needle to embed 1-cm long catgut segments in an acupoint, enabling the catgut to perform long-term stimulation of the acupoint and achieve the effects of acupuncture treatment. Each therapy process requires numerous repetitions of the same steps, and each needle set can only be used to embed one catgut segment. Additionally, doctors must perform this surgical procedure by hand; no automatic auxiliary instrument has been developed to date. To address these problems, this paper proposes an innovative design of the first automatic ACE auxiliary instrument in the world. The instrument could assist doctors to complete the ACE steps. And it neither requires a battery or external electric power nor changes needles during therapy. The study first involved designing the mechanism and embodiment for the instrument, enabling it to perform one catgut-embedding procedure in only two steps with the repeated use of one needle set. We then created the prototype and tested its functionality in terms of the success rate of catgut cutting, average length of catgut segments, the success rate of needle insertion and acupoint range, and the success rates of catgut insertion and catgut embedding. The results showed that the prototype did conform to our design goals, but the success rates of catgut cutting and catgut insertion could be further enhanced.