The difference between three-dimensional color Doppler ultrasound and four-dimensional color Doppler ultrasound lies in the impassability of time dimension parameters, that is to say, three-dimensional color Doppler ultrasound is a picture and four-dimensional color Doppler ultrasound is a video, so that pregnant women can see a series of fetal movements. Four-dimensional color Doppler ultrasound is dynamic and three-dimensional color Doppler ultrasound is static, so four-dimensional color Doppler ultrasound can only be a photo at a certain point in time, while four-dimensional color Doppler ultrasound can make a series of actions into multimedia. In screening fetal malformations, three-dimensional color Doppler ultrasound and high-definition four-dimensional color Doppler ultrasound can also remove malformations, but high-definition four-dimensional color Doppler ultrasound is more accurate.