Abstract： Objective To investigate the etiology, diagnosis and prognosis of fetal ascites. Methods A retrospective analysis on prenatal diagnosis and pregnant outcomes was performed on 79 singleton pregnancies presenting with fetal ascites through ultrasound scan. Results Among the 79 cases, ultrasound scan indicated 56 cases (70. 9%) of fetal ascites were the menifestation of fetal hydrops and 23 (29. 1%) were isolated cases. Twenty-nine (51.8%) out of the 56 cases of hydrops fetalis presented with cardiac enlargement, and digestive deformities, respiratory and cardiac malformations were commonly seen. Etiology exploration showed 30 cases with alpha-thalassernia, intrauterine infection in 9 cases, organic malformation in 19 cases, 3 cases with matenal-fetal Rhesus alloimmunization, 1 case with Turner syndrome and 1 trisomy-13. The rest 16 cases were idiopathic, thus etiology could be determined in 79. 7% of the 79 cases. During the follow-up, 64 women elected to terminate their pregnancies (5 fetal deaths), 13 full term delivered among which 10 livebom infants survived beyond the neonatal period, including 7 cases of meconium peritonitis and 3 idiopathic ascites, and 2 were lost. Conclusions The etiology of fetal ascites are various, mainly including alpha-thalassemia, organic malformations and intrauterine infection. Isolated fetal ascites, especially fetal ascites caused by meconium peritonitis, have a better prognosis. A systematic protocol is recommended to reach etiology diagnosis and prognosis prediction.