Objective　 To observe the clinical effect and prognosis of oral sirolimus in the treatment of abdominal lymphatic malformations. Methods　From March 2020 to August 2022， clinical data of 5 patients with abdominal lymphatic malformations treated with oral sirolimus were retrospectively analyzed. Results　 All patients had abdominal pain before admission and were treated with oral sirolimus for 2 years. Subjective evaluation of clinical symptom improvement： Progress in 0 case， stability in 2 cases， improvement in 3 cases， cure in 0 case. Objective evaluation of lesion improvement： Grade Ⅰ（poor） in 2 cases， grade Ⅱ（ medium） in 0 cases， grade Ⅲ（ good） in 1 case， grade Ⅳ（ excellent） in 2 cases. During the treatment， 2 patients developed oral ulcers and 1 patients developed mild anemia， all of which were improved after symptomatic treatment. All patients had no serious complication. After 1 year of follow-up， abdominal pain and other symptoms did not appear again， and the tumors of 3 cases （macrocystic lymphatic malformations） were significantly reduced， and 2 cases （microcystic lymphatic malformations） did not show significant tumor growth. Conclusion　Sirolimus is safe and effective in the treatment of abdominal lymphatic malformations， and can significantly relieve abdominal discomfort symptoms， especially for macrocystic lymphatic malformations， with significant tumor size reduction and satisfactory results.