Objective:To investigate the clinical value of echocardiography in the diagnosis of fetal arrhythmia.Methods:1 500 pregnant women who underwent a regular prenatal examination in Cangnan Hospital Affiliated to Wenzhou Medical University from March 2018 to March 2020 were included in this study. These pregnant women underwent fetal echocardiography in the second trimester of pregnancy (24-26 weeks). We evaluated the condition of, and calculated the incidence of, fetal arrhythmia complicated by fetal cardiac structure abnormality . The diameters of the descending aorta, umbilical artery, and middle cerebral artery were compared between normal fetuses and arrhythmia fetuses.Results:Fetal arrhythmia was found in 131 pregnant women who were in the second trimester of pregnancy, with an incidence of fetal arrhythmia of 8.73%. Fetal arrhythmia and cardiac structure abnormality were detected in 19 pregnant women, with an incidence of fetal arrhythmia and cardiac structure abnormality of 1.27%. Fetal arrhythmia was detected in 131 (8.73%) pregnant women who were in the second trimester of pregnancy and it was detected in 32 (2.13%) pregnant women who were in the third trimester of pregnancy. Arrhythmia was detected in 18 (1.2%) newborns. Only 5 (0.33%) fetuses died during the perinatal period. Four (0.27%) fetuses had arrhythmia complicated by cardiac structure abnormality. One (0.07%) fetus was normal. The diameters of the descending aorta and middle cerebral artery were greater in normal fetuses than in arrhythmia fetuses in pregnant women who were in the second trimester of pregnancy, and the diameter of the umbilical artery was significantly smaller in normal fetuses than in arrhythmia fetuses ( t = -8.27-19.62, all P < 0.001). Conclusion:Echocardiography can effectively help diagnose fetal arrhythmia and observe abnormal cardiac structure. The imaging technique is of great clinical value in improving the diagnosis and treatment of fetal arrhythmia.