Objective To explore the feasibility of using transverse ultrasound to observe the intracranial posterior brain structure of fetuses in 11-13+6 gestational weeks, so as to shorten the examination time while effectively screening the intracranial structure of fetuses in early and middle pregnancy. Methods 2695 normal fetuses of 11-13+6 gestational weeks were randomly selected to obtain the mid-sagittal and transverse sections of the brain. The structure of the posterior brain was observed and the thickness of the intracranial transparent layer was measured. Results Of the 2695 fetuses, 2402 received mid-sagittal and posterior transverse sections of the brain, and 239 received only posterior transverse sections of the brain, but no mid-sagittal sections of the brain were obtained. The structure of "two high and three low echo cords" in fetal posterior brain was observed on sagittal section and transverse section. The IT values measured on two sections of 2402 fetuses were analyzed by Bland-Altman software. The IT values measured in the two sections are in good agreement. Conclusion Posterior transverse section and sagittal section of the brain can effectively observe fetal posterior brain structure, but fetal posture restricts the acquisition of posterior transverse section. The use of this section can improve the work efficiency of ultrasound doctors. At the same time, for fetuses with poor posture, transverse section of the posterior cranial fossa provides an effective way to observe fetal brain structure.