MRI techniques were developed in the late 1970s and early 1980s. 1983 was the first time that Smith et al. reported the application of MRI to the fetus, and in 1985 Weinreb et al. began to use MRI for the detection of normal anatomy of fetal tissues and organs. The application of fetal MRI in China started in 1995. MRI has shown unique advantages in prenatal diagnosis of fetal defects because of its multi-directional imaging, high soft tissue resolution, no radiation, and safety to the fetus. In this study, MRI was further performed on fetuses with ventricular dilatation suggested by ultrasonography to investigate the clinical value of MRI in the diagnosis of fetal ventricular dilatation and to follow up the prognosis of fetuses with ventricular dilatation. Diagnostic criteria: ventricular dilatation was detected by ultrasonography, and MRI was performed to further clarify the diagnosis; fetuses with unilateral or bilateral ventricular triangle width of 10-15 mm were diagnosed as mild ventricular dilatation, those with 16-20 mm were diagnosed as middle ventricular dilatation, and those with 20 mm were diagnosed as severe ventricular dilatation. A case-control study was conducted to determine the intellectual growth and development of fetuses with simple mild lateral ventricular dilatation diagnosed by MRI and fetuses without abnormalities from six months to one year after birth using the Denver Intelligence Developmental Screening Scale. Among 135 fetuses with ventricular dilatation diagnosed by ultrasound, 56 cases (41.5%, 56u135) had no significant abnormalities on MRI, 60 cases (44.4%, 60u135) had simple ventricular dilatation, 5 cases (3.7%, 5u135) had ventricular dilatation combined with cerebral hemorrhage, and 2 cases (1.5%, 2u135) had ventricular dilatation combined with cerebellar hypoplasia. 1.5%, 2u135), 12 cases of ventricular dilatation combined with g-body abnormalities (8.9%, 12u135), and 79 cases of fetal ventricular dilatation diagnosed by MRI, of which the rate of combined g-body abnormalities was 15.2% (12u79). Of the 79 cases of fetal ventricular dilatation diagnosed by MRI, 30 fetuses with mild ventricular dilatation and 5 fetuses with moderate ventricular dilatation were gestated to full term, and no infant abnormalities were found at postnatal follow-up; 7 other cases refused to cooperate, 6 pregnant women firmly requested induction of labor, and 12 cases were lost. Among the 12 fetuses with combined g-body abnormalities, 3 continued the pregnancy and the fetuses were born with the same diagnostic results as the fetal MRI examination, while the other 8 pregnant women insisted on induction of labor and 1 case was lost. In 5 cases of fetuses with cerebral hemorrhage, all of them were induced according to the pregnant women’s wish, and the postmortem examination confirmed the correct diagnosis of MRI. 2 cases of fetuses with cerebellar hypoplasia, 1 continued the pregnancy to full term and the baby was diagnosed with cerebral palsy 6 months after birth, and the other case was induced. Conclusion: MRI is one of the best methods to determine fetal ventricular dilatation and other parenchymal brain abnormalities: the degree of ventricular dilatation and whether it is combined with other central nervous system abnormalities are important in determining the prognosis. In the prenatal diagnosis of fetuses with ventricular dilatation, ultrasonography is still the common method of screening, but MRI can make a more accurate determination of the degree of fetal ventricular dilatation and the development of the surrounding brain parenchyma. In fetuses with simple ventricular dilatation confirmed by ultrasonography, further MRI can detect fetal ventricular dilatation combined with other abnormalities in more than 50% of cases. The results of this study showed that among 135 fetuses with ventricular dilatation detected by ultrasonography, further MRI examination revealed 5 cases of combined cerebral hemorrhage, 12 cases of combined g-body abnormalities, and 2 cases of combined cerebellar hypoplasia. The use of MRI for the detection of fetal ventricular dilatation with comorbidities is of great clinical significance and can help the physician to predict the outcome of the pregnancy to a great extent and help the mother to decide on the choice of the fetus.