Due to the lack of specificity of clinical manifestations and laboratory tests of fatty liver, ultrasound has the advantages of being economical, rapid, accurate and non-invasive, and should be listed as the primary examination method for this disease. 1.Diffuse fatty liver: According to the degree of echogenic attenuation, there are three degrees: (1) Mild: anterior field echogenic enhancement, posterior field echogenic attenuation is not obvious, and intrahepatic tubular structures are still visible. (2) Moderate: Echo enhancement in the anterior field, attenuation in the posterior field, and blurring of tubular structures, but still recognizable. (3) Echo enhancement in the anterior field, attenuation in the posterior field, or even an echogenic area with indistinct contours and indistinguishable tubular structures. 2.Limited fatty liver: limited fatty liver is also called non-uniform fatty liver, as opposed to diffuse fatty liver, and the two can be transformed into each other. In the first stage, it is limited to a small piece of liver parenchyma, and the sonogram appears as multiple strongly echogenic nodules, which can then develop into a non-uniform diffuse fatty liver. The entire liver is diffusely infiltrated, with only small areas of normal or relatively normal parenchyma remaining, mostly in the subhepatic peritoneum, gallbladder bed or portal vein trunk branching area, most often in the left lobe of the liver, which appears as a weakly echogenic area with clear margins in the strongly echogenic liver parenchyma, in the form of a circle-like or patchy pattern, but without mass effect, without vascular bypass or interruption, and even with normal extension of the portal vein into the area. It can be divided into three types: (1) limited infiltrative type: it appears as small intrahepatic patches of strong echogenic clusters. (2) Lobular infiltrate: the fatty infiltrate is more extensive and the area involved coincides with the lobular extent of the liver. (3) Diffuse non-homogeneous infiltration type: Most of the liver parenchyma is infiltrated by fat, with small patches of normal areas showing weak echogenic areas.