Aneurysm is a very dangerous disease and can be life-threatening if it ruptures. The concept of pseudoaneurysm exists clinically, and the difference between true aneurysm and pseudoaneurysm is mainly as follows: 1. True aneurysm: The lumen diameter of the arterial duct is more than 50% of the normal arterial diameter, and the aneurysm is actually a part of the artery, which is a pulsatile manifestation of the local expansion of the arterial wall at the weaker location. Aneurysms have the normal structure of the original artery, with three layers, including the outer membrane, inner membrane and central fibrous elastic layer. Aneurysms occur mainly in larger vessels, mainly in the aorta. The blood vessels in the aneurysm part are weak, so if they are hit or the blood pressure suddenly increases, it may cause the aneurysm to rupture suddenly, and its good site is in the large blood vessels, so once the aneurysm ruptures, if it cannot be rescued in time, the patient’s probability of survival is extremely low; 2. Pseudoaneurysm: Actually, after the artery is damaged, the blood flows out from the arterial wall and forms a hematoma locally in the arterial wall. The local fibrous tissue wraps around it and forms a pseudo-lumen, which is then clinically referred to as a pseudo-aneurysm. The outer wall of a pseudoaneurysm is hyperplastic fibrous tissue, and the inner wall is normal intima. If the pseudoaneurysm can be repaired, the vessel can be restored to its normal structure.