At present, the common detection methods of ultrasound Doppler flow include CDFI, PW, CW, SMI: 1, CDFI is color Doppler flow imaging, it is the Doppler information obtained for processing color gray scale coding, with red and blue different colors and brightness to identify the direction of blood flow and the size of the speed, and superimposed on the B-type ultrasound sonogram, red represents the direction of blood flow toward the probe, blue CDFI is used to observe the filling status, distribution, and velocity of blood flow in real time. 2. Spectral Doppler applies the curve formed by frequency shift to determine the direction and velocity of blood flow, including pulsed spectral Doppler (PW) and continuous spectral Doppler (CW). Positioning probing, CW can be used to measure higher speed blood flow without positioning and depth resolution. 3. ultramicroscopic flow imaging (SMI), which can clearly see the blood flow status of new microscopic vessels, is used for low speed blood flow that is not detected by conventional ultrasound.