MRI was first used for fetal examination for more than 20 years abroad, and most large hospitals in China have also carried out this examination, mainly for fetal evaluation and diagnosis of congenital developmental abnormalities. It has become an important complementary tool to prenatal examination, providing clinicians with more and more reliable information to decide whether to terminate a pregnancy. The preferred method of fetal imaging is ultrasound, so what are the conditions that require fetal MRI? First, cases in which ultrasound cannot provide diagnostic information due to maternal obesity, low amniotic fluid, uterine adenomyomatosis, fetus already in the pelvis, posterior fetal cranial fossa abnormalities in the second trimester and fetal position changes. Second, fetal central nervous system anomalies that have been identified by ultrasound or cannot be identified, MRI can provide additional complementary information. Third, complex fetal anomalies, such as congenital cystic adenomatoid malformation of the lung, congenital diaphragmatic hernia, and pulmonary isolation. Fourth, evaluation of fetal abdominal anomalies. Fifth, evaluation of placental anomalies and high risk. Compared with ultrasound, MRI has a large field of view, good soft tissue contrast, high quality display of fetal organs, and is better for evaluating the spatial relationship of fetal anatomical abnormalities and the relationship between larger lesions and surrounding structures. However, MRI does not show all morphological abnormalities of the fetus, for example, some anomalies of the body surface and some extremities are not well visualized due to the fetal body position.