Abstract：【Objective】To investigate the application value of four-dimensional ultrasound with high definition flow（HD flow） in the observation of fetal pulmonary vein.【Methods】From June 2015 to June 2016，130 fetuses in our hospital underwent prenatal fetal echocardiography were included in this study. Color Doppler and high definition flow imaging were used to observe and count the number of pulmonary veins in the fetal four chamber view. In the condition of opening HD flow，the 3D volume data was collected from the heart of the fetal four chamber view，and the 3D images of the fetal pulmonary vein were obtained by using the post processing software. Comparisons were made between the three methods for visualization numbers of the normal fetal pulmonary veins. For 5 cases of abnormal pulmonary venous drainage，STIC combined with HD flow technique was used to carry out three-dimensional reconstruction of pulmonary veins，to observe the abnormal drainage.【Results】The display rate of HD flow on fetal pulmonary veins was higher than that of color Doppler. For the 17 ~ 32 weeks fetal，four-dimensional ultrasound combined with HD flow could better observe the spatial location of pulmonary veins.【Conclusions】STIC combined with HD flow technology can display fetal pulmonary veins better in the second and early-third trimester of pregnancy，and three-dimensional reconstruction of the image is more intuitive，helpful to understand the spatial relationship.