Manual acupuncture (MA), as a mechanical action, can be equivalent to an external stimulus to the neural system. However, the regulation and action mechanism of acupuncture is still unclear. In the present study, synchronization levels of brain activities evoked by MA is investigated. We design an experiment that acupuncture at Zusanli with four different frequencies to obtain electroencephalograph (EEG) signals. Since neural system is a complex nonlinear dynamics system that possesses strong nonlinear characteristic, phase synchronization (PS) based on recurrence plot method is introduced to quantify the synchronization between EEG signals induced by MA. It is found that the synchronization between different brain regions during acupuncture is obviously lower than that before acupuncture, which can prove that MA has effect on the brain.