The lymphangioleiomyomatosis(LAM) is a rare disorder, which afflicts mainly young woman of childbearing age, characterized by proliferation of immature smooth muscle cell in the lymphatics. We experienced a case of LAM in 26-years-old pregnant woman, confirmed pathologically by inguinal lymph node biopsy. She has suffered from exertonal dyspnea and dry coughing. The symptoms and chest X-ray were aggravated with pregnancy, but improved after delivery with two times of pregnancy. The chest X-ray showed diffuse reticulonodular infiltration and chest HRCT showed diffuse scattered tiny thin-walled cyst of lung parenchyma. We noted chylous ascites of which triglyceride level is 396 mg/dl. After delivery, the symptoms were getting better. We treated with medroxyprogesterone and planned close observation and follow-up.