【】Objective Utilizing the 2D and 3D tomographic ultcasound imaging(TUI),TUI technique observe the integrity of the postnasal triangle in 11-13 weeks. To compare and evaluate the function of the two-dimensional ultrasound and the three-dimensional tomographic ultrasound imaging (TUI) in measuring the postnasal triangle of the fetuses in 11～13 weeks. Materials and methods 150 fetuses were chosen with Crown-Rump Length (CRL) around 45-84mm to watch the Retronasal fetal postnasal triangle ’s integrity by using 2D and 3D ultrasound respectively in facial ministry inclined coronal view. The 2D and TUI ultrasound technique were used in facial inclined coronary view prospectively to measure the fetal postnasal triangle vertex angle at 100 pregnant women in early pregnancy.Results The inclined coronary views,the midsagittal views and the fetal postnasal triangle vertex angle could obtained by both 2-dimensional ultrasound and TUI. Also they could observe the continuity of the retronasal triangle and palate.Conclusion Determine the retronasal triangle by both 2D and TUI during the first trimester of pregnancy could provide a reference for screening cleft palate. Two-dimensional ultrasound can be faster and more direct to scan the postnasal triangle, observe theexistence of interrupt, and diagnosis the existence of cleft palate. TUI can detecte the retro nasal triangle and its vertex angle rapidly. The volume data based on the inclined coronary views can obtain more complete and legible postnasal triangle views.