Abstract: There are physical differences between laser and needle acupuncture. It suggests that their therapy mechanisms are different. A bio-energetic model has been developed to explain laser heat effects and a ray optics regime to illustrate optical forces. Then the mechanism of laser acupuncture is studied from the viewpoint of photon traditional Chinese medicine and principle of physics. The affected factors and optimal light dosage on laser acupuncture therapy are also discussed from a theoretical point of view .