Background: Dry eye syndrome, which affects 10% to 20% of adults, is a disorder of the tear film and is associated with symptoms of ocular discomfort. Smart Plug is a mechanical treatment in which the tear drainage system is blocked in order to aid in the preservation of natural tears on the ocular surface. Purpose: To evaluate the long-term clinical efficacy of Smart Plug in the treatment of aqueous tear deficiency dry eye. Patients and Methods: Retrospective study. Three hundred and two patients with aqueous tear deficiency dry eye were enrolled and all the patients accepted the punctual plug of Smart plug from Jan. 2011 to Jan. 2016. The clinical symptoms, Schirmer’s I test, Fluorescein staining (FL), tear break up time (TBUT), and complications were observed and analyzed. Results: Three hundred and two patients (604 eyes) were treated with Smart Plug (22 cases accepted upper and lower punctual plug, 280 cases only lower punctual plug). There were 109 males (36.1%) and 193 females (63.9%) with a mean age of 44.54 years old (Range from 25 to 83 years). Ten cases required the upper Smart Plug after lower punctual plug insertion because of no significantly improved symptoms. Smart plug was removed in 3 patients (1%) due to tearing. Six patients had mild postoperative tearing and no special treatment was required. Lacrimal canaliculitis occurred postoperatively in 8 cases (2.6%) (6 lower and 2 upper), and the affected plug was removed and treated with topical antibiotic eye drops. The BUT, SIT and FL scores of all patients were significantly improved from (2.11 ± 1.01, 4.20 ± 1.07, 6.06 ± 1.97) to (4.34 ± 1.22, 9.01 ± 1.56, 2.33 ± 1.28) respectively after at least 36 months of follow-up (All P P Conclusion: During a mean follow-up of 4.3 years, Smart plug is an effective method for the treatment of aqueous tear deficiency dry eye in spite of its postoperative complications such as canaliculitis and tearing.