Although mammalian brain O-glycans account for only small amounts (~1%) of total brain glycans, it is closely related to neuro-biological processes such as synaptic plasticity and memory formation. Although GALNT (Polypeptide N-acetylgalactosaminyltransferase) is a major enzyme responsible for the synthesis of Tn antigen epitope in neurons, little is known about the association of GALNT expression with physiological and pathological brain functions. In this study, we compared brain O-glycan profiles obtained from GALNT13 KO mouse and wild type mouse (C57BL/6J), respectively in order to figure out specific biological functions of GALNT13 which is one of GALNT family. Briefly, brain tissues were grinded and sonicated for homogenization. Membrane was extracted using ultracentrifuge for O-glycan enrichment. O-glycans were chemically liberated by β-elimination from homogenized brain tissue., Purified and enriched O-glycans using PGC-SPE were chromatographically separated and identified by PGC(column) UPLC coupled with Q-TOF mass spectrometer. Structure information of O-glycans were obtained by tandem MS. This study would provide useful information on brain O-glycome which has languished in relative obscurity.