Objective To explore pre-attentive information processing in undergraduate students with major depressive disorder(MDD) indexed by auditory mismatch negativity (MMN) and provide scientific theory basis for the diagnosis of MDD. Methods In the deviant-standard reverse oddball paradigm with deviant stimulus presentation probability of 20%, duration auditory MMN was obtained in 17 MDD university students and 17 gender-/age- matched healthy undergraduate students. All data were analyzed by statistics means of repeated measurement of F test. Results The amplitudes of 150 ms MMN over the frontal-central area were smaller in MDD undergraduate students((-0.34±1.24) μV) than those in healthy undergraduate students ((-1.07±1.55) μV, F=24.318, P=0.000). The 50 ms MMN did not differ between MDD students((-1.96±1.14)μV) and healthy undergraduate students ((-1.23±1.97)μV, F=0.089, P=0.767). Conclusion Pre-attentive auditory information processing is impaired in MDD undergraduate students. Key words: Major depressive disorder; Undergraduate students; Pre-attentive processing; Mismatch negativity