Patients often come with their medical reports to ask: What should I do if my blood viscosity is high? In some hospitals, blood viscosity test is a routine test for patients with cardiovascular diseases. Some doctors believe that high blood viscosity means high blood lipids, and blood vessels are easily blocked and prone to myocardial infarction. But in fact, due to the lack of accurate test results, blood viscosity has become a “junk indicator” with little reference significance. There are no drugs that can really reduce blood viscosity. Most of the world’s leading hospitals do not test blood viscosity in their cardiology departments. Many years ago, when the mechanism of thrombosis was not known, the concept of blood viscosity was explored in the context of physics. Many indicators are not measured directly but are calculated by formulae, which are not reproducible and are influenced by many factors; at the same time, the results of in vitro experiments usually do not fully reflect the rheological properties of blood in vivo and can only be used as a clinical reference. Now it has been clarified that the main causes of cardiovascular and cerebrovascular events are inflammation and hyperlipidemia. Under the influence of risk factors such as hypertension, diabetes, smoking and obesity, which lead to arteriosclerosis, the rupture of hardened plaque, platelets gather together and form thrombus, leading to myocardial infarction and cerebral infarction. Therefore, the indicators to be checked should be the level of blood lipids, coagulation routine, inflammation indicators, atherosclerosis indicators, platelet activity, etc. And no longer check the indicator of blood viscosity. Preventive and therapeutic measures mainly include: quit smoking, limit alcohol, healthy diet, strengthen exercise, control weight, regulate blood lipids, antiplatelet, anti-atherosclerosis, etc.