This paper reported the observed results on changes of the infrared thermal image of upper extremity induced by needle "Hega" (LI 4), "Daling" (P 7) and "Neiguan" (P6) points. The results indicated that 10 out of 23 cases whose higher and middle temperature bands of upper extremity distributed along the "Dachang" (Large Intestine) channels, when they felt phenomena of propagated sensation along the "Dachang" channels induced by needle "Hegu" points. Those effects did not appear in the objects who did not feel PSC along the "Dachang" channels induced by needled points. Above results provide an objective basis for the phenomena of channels and suggest that the phenomenon of PSC is an objective fact in human body.