This study performed integrated intact N- and O-glycoproteomic profiling of human serum from normal controls (n=10), patients with mild cognitive impairment (MCI, n=10), and patients with Alzheimer's disease (AD, n=9). A total of 2,433 intact N-glycopeptides and 3,864 intact O-glycopeptides were identified, providing a site-resolved view of systemic glycosylation changes during disease progression. Quantitative analysis revealed distinct remodeling patterns for N- and O-glycosylation, with early reduction of IGHG1 Asn180 N-glycoforms at MCI stage and progressive increase of APOE O-glycoforms from control to MCI and AD.