Objective:To analyze the fetal ultrasonographic features of malformation of cortical development (MCD) during the second trimester, and explore and summarize the relevant diagnostic clues, so as to improve the ability of diagnosis and differential diagnosis of fetal MCD.Methods:A total of 313 fetuses with brain abnormalities suspected on ultrasound in Chengdu Women′s and Children′s Central Hospital from April 2018 to August 2022 were retrospectively analyzed. The fetuses were examined using MRI. The ultrasonographic characteristics of fetal MCD were summarized, and the fetal ultrasound and MRI imaging data were compared for fetal MCD.Results:Nineteen fetuses were diagnosed with MCD from 313 fetuses(6.07%, 19/313). Seventeen cases of MCD were identified by ultrasonography and subsequently validated by fetal MRI, including 6 cases of schizencephaly, 2 cases of hemimegalencephaly(HMEG), 3 cases of periventricular nodular heterotopia(PVNH), 3 cases of lissencephaly, 2 cases of microcephaly and 1 case of polymicrogyria(PMG). There were 3 cases with two concurrent MCD, 1 case of HMEG, and MRI increased the diagnosis of left parietal PMG; 1 case of lissencephaly, and MRI increased the diagnosis of PVNH. The other case was PMG, and MRI increased the diagnosis of lissencephaly. Two cases of fetal MCD were not indicated by ultrasonography, one of which was diagnosed as tuberous sclerosis and another one as schizencephaly by MRI, both due to ventriculomegaly.Conclusions:Various types of MCD in the second trimester have ultrasonographic characteristics. Abnormal lateral ventricles, intracranial structural changes such as sulci and gyrus can provide reliable ultrasound diagnostic clues for fetal MCD.