Aimed at exploring the mechanism of acupuncture therapy, we develop functional brain networks using electroencephalogram (EEG) data, and use the methods cluster coefficient to analyze the functional networks. We develop the following result: during the acupuncture, the structure of network becomes tighter, the relativity grows stronger and the structure of the networks becomes complex. Our conclusion is that acupuncture is able to affect the firing properties of the central nervous system, and make the information transmission in the brain functional sections stronger.