Resting state functional MRI (rs-fMRI), which is used to measure blood oxygen level-dependent (BOLD) from resting brains, is a relatively new and powerful method for evaluating regional interactions that occur when a participant is not performing an explicit task. Because of the sensitiveness to the phase shift and length of time courses of the BOLD recordings, region of interest based conventional correlation and coherence methods are no longer suitable for rs-fMRI analyses. In this paper, we propose a more robust and consistent method, dominant frequency mapping, to analyze rs-fMRI data. We found a dominant frequency of BOLD recordings, 0.0137Hz, in resting human brains that is consistent across participants and brain regions. This frequency is detected mainly in Gyrus Rectus, Frontal Medial Orbital, Frontal Superior Orbital and Olfactory Sulcus, which control the human social behavior, emotion, and decision making. In the meantime, we found that BOLD frequencies are most inconsistent in the brain regions of PrecentralGyrus, Superior Frontal gyrus, Insula, Caudate nucleus, Putamen, and part of the cerebellum, whose functions are about motor.