Major depression disorder (MDD) is a serious mental illness with high disability rate and high recurrence rate, accompanied by cognitive impairment including language processing. This article reviews neurophysiological evidences of abnormal semantic processing in MDD patients in recent years. Electrophysiological data indicates that abnormal semantic processing in the patients begins in the early stages of perceptual processing and persists in subsequent cognitive processing stages with hemispheric lateralization. Brain imaging studies show that the patients have abnormal activation levels in the medial prefrontal cortex and inferior frontal gyrus. The current research paradigms cannot separate semantic processing from other cognitive processes, and more research is needed.