Fetal septum pellucidum 11mm at 36 weeks is abnormal and requires further investigation for brain malformations and chromosomal abnormalities. The septum lucidum is an important structural marker for normal development of the fetal central nervous system. The normal range of septum lucidum should not be more than 10mm, and its width will change according to the increase of gestational weeks and the size of the fetus itself. The hyaline septum widens with each week of pregnancy until 36 weeks of pregnancy, but in most pregnancies, the fetal hyaline septum begins to narrow again after 36 weeks of pregnancy, or even closes and cannot be visualized. It is generally considered that a fetal septum lucidum greater than 10mm is a dilated septum lucidum, suggesting that there may be central nervous system developmental abnormalities, poor prognosis of the fetus, etc., and further investigation should be made to determine whether there are brain malformations and chromosomal abnormalities. Pregnant women should pay attention to the prenatal examination during pregnancy, actively listen to the advice of professional doctors to do a comprehensive nursing care, pay attention to rest, at the same time should relax, avoid tension, anxiety, any discomfort should be timely to the hospital, by the doctor to clarify the diagnosis, and cooperate with the doctor to deal with the symptoms.