C-Reactive protein (CRP), discovered in 1930, is an acute time-phase reactive protein that reacts with pneumococcal C polysomes to form a complex. In recent years, due to the progress of testing technology, CRP is widely used in the early diagnosis, differential diagnosis and prognosis assessment of clinical diseases, and its diagnostic value is very important. 1, CRP correlates with the severity of the disease: as an acute reactive protein in a variety of acute inflammation, tissue injury, myocardial infarction, surgical trauma, radiation damage and other disease episodes in a few hours after the rapid increase, with the severity of the disease multiplied. 2. CRP is associated with inflammatory factors: CRP is closely related to other inflammatory factors such as total leukocyte count, blood sedimentation and neutrophils. CRP may rise earlier than WBC during the patient’s disease attack. 3.CRP is used for the differential diagnosis of bacterial and viral infections: once bacterial inflammation occurs, CRP levels are elevated, while viral infections CRP is mostly normal. 4.Indicator of postoperative infection and complications: CRP is elevated in patients after surgery, and the level of CRP should decrease 7-10 days after surgery, if CRP does not decrease or increases again, it suggests possible complication of infection or thromboembolism. 5, CRP is mostly elevated in patients with malignant tumors. For example, the combined test of CRP and AFP can be used for the differential diagnosis of hepatocellular carcinoma and benign liver diseases. 6, CRP and amylase as well as lipase are used to assess the severity of acute pancreatitis. When CRP is higher than 250 JuL, it can suggest extensive necrotizing pancreatitis. 7, a strong independent predictor of cardiovascular disease: hypersensitive C-reactive protein (HS-CRP) and CRP are not two proteins, but are distinguished by their sensitivity, with hypersensitive C-reactive protein being more sensitive to low values. mildly elevated HS-CRP is associated with coronary events, stroke and peripheral vascular disease; HS-CRP is an independent risk factor for cardiovascular disease triggered by chronic inflammation, and its concentration is important for HS-CRP is an independent risk factor for cardiovascular disease caused by chronic inflammation, and its concentration plays an important role in the intervention and prognosis of cardiovascular disease; elevated HS-CRP levels are two times more likely to cause acute stroke and three times more likely to cause myocardial infarction than normal healthy individuals; HS-CRP is also an independent predictor of atrial fibrillation and has some correlation with hypertensive disease. C-reactive protein values in normal healthy individuals are low, typically <0.8 mg/L, and 99% of normal individuals have C-reactive protein <1.0 mg/L.