4D ultrasound is the computer processing of several different flat 2D images acquired continuously to obtain a reconstructed graphic with a three-dimensional sense. 4D ultrasound is the joint application of ultrasound equipment and high-speed computer equipment, thus improving the speed of data processing and making it clinically practical. The 4D ultrasound used in the clinic now is the real real-time 3D ultrasound obtained by the latest development of high-speed volume imaging. The application of 4D ultrasound in clinical practice is relatively wide. In clinical applications, it is possible to obtain arbitrary flat images and mark the spatial location and direction of the observed target, reducing the interference of subjective factors. 4D ultrasound has powerful data acquisition and display speed, and is able to perform various calculations accurately. The reconstruction of 4-D stereoscopic images of the structures to be examined allows doctors, patients and their families to have a more visual and clearer understanding of what is being examined. For the examination of the fetal period, the use of stereoscopic images allows for a more detailed observation of the abnormal areas of the fetus, thus allowing for a complete picture of the lesion. The application of 4D ultrasound is multifaceted and can provide more and more comprehensive diagnostic information for clinical purposes.