Spider nevus is an idiopathic capillary dilatation that can manifest as a radial dilatation of small blood vessels, as if it were a spider, which is why it is called a spider nevus. It occurs mainly in the area where the superior vena cava is distributed, such as the face, shoulder, upper limbs, upper chest and neck. It is common in patients with cirrhosis of the liver, which can lead to the appearance of spider nevus in the above areas due to the decrease in the inactivation of estrogen by the liver and the high pressure of the portal vein. Spider nevi can also appear in normal healthy people, such as children and pregnant women. Normally, the nevus can be removed by pressing on it with the hand. However, if a spider nevus appears in a normal person, we don’t need to pay much attention to it. However, if spider nevi appear in patients with cirrhosis, it means that cirrhosis has developed to a certain degree, and then we should consult the doctor in time to find out whether there are other serious complications of cirrhosis, and give active treatment.