Alzheimer's disease (AD) is a severe neurodegenerative disease with heavy social burden. Current drugs cannot reverse disease progression. Brain glymphatic system and meningeal lymphatic dysfunction lead to impaired clearance of Aβ and Tau protein, which is an important pathogenesis of AD. Deep cervical lymphovenous anastomosis (DCLVA) can improve intracranial lymphatic drainage, promote the clearance of toxic proteins, and improve neurological function. This is a single-arm, prospective, self-controlled study to enroll 59 patients with severe AD (MMSE \< 10). All patients receive bilateral DCLVA plus routine medication. The primary endpoint is change of CDR-SB score at 12 months post-operation. Secondary endpoints include MMSE, ZBI scores and Aβ PET-CT Centiloid value. This study aims to verify the efficacy and safety of DCLVA for severe AD.