Objective:To observe the changes of metabolic intensity value of points on the face before and after needling bilateral Hegu (LI 4) in healthy people and provide scientific basis for association between Hegu (LI 4) and face/mouth. Methods:A total of 45 healthy college students were selected in this study. Using medical thermography and Pennes bio-heat transfer model, the infrared thermograph images on the face before and after needling bilateral Hegu (LI 4) were collected to observe the distribution of metabolic intensity value on the face before acupuncture and changes in these values after needling bilateral Hegu (LI 4). Results:Before acupuncture, Cuanzhu (BL 2) had the maximal metabolic intensity value. Its mean value was (0.71±0.23) W. Quanliao (SI 18) had the minimal metabolic intensity value. There were no left-right statistical significances in metabolic intensity values. After needling bilateral Hegu (LI 4), the metabolic intensity values of most points on the face were increased. Kouheliao (LI 19) obtained the maximal increase: 0.35 W on average; and Yangbai (GB 14) obtained the minimal increase: 0.08 W on average. Conclusion:Points on both sides in healthy people have good symmetry in metabolic intensity value. After needling bilateral Hegu (LI 4), the metabolic intensity values of points on the face were increased, especially points around the lips, which accords with the pathway of the Large Intestine Meridian on the head and face. This provided some scientific foundation for the association between Hegu (LI 4) and face/mouth.