Mild, moderate and severe fatty liver are mainly distinguished by imaging examination of the liver, liver function and fat attenuation index. 1. Imaging examination: ultrasound of mild fatty liver shows near-field echo enhancement, far-field echo attenuation is not obvious, and tubular structure is still visible in the liver; ultrasound of moderate fatty liver shows anterior field echo enhancement and posterior field echo attenuation; ultrasound of severe fatty liver shows significant enhancement of near-field echo and far-field echo attenuation. 2. Liver function: if liver function is basically normal, it may suggest mild fatty liver; mild abnormal liver function may suggest moderate fatty liver; moderate or severe abnormal liver function may suggest severe fatty liver. 3. Fat attenuation index: if the attenuation degree is between 240 and 265, it may indicate mild fatty liver; if the fat attenuation index is between 265 and 295, it may indicate moderate fatty liver; if the fat attenuation index is greater than 295, it may indicate severe fatty liver. It is suggested that patients with fatty liver should go to the hospital in time to judge the severity of fatty liver under the guidance of professional physicians and intervene as early as possible, rather than judging blindly by themselves.