There is no exact figure for the normal value of routine blood CRP, which is related to the way of testing and the instrument, and its approximate range is around 0-10 mg/L. Blood CRP refers to C-reactive protein, which is a protein that rises sharply in the plasma when the body suffers from infection or tissue damage, and can effectively enhance the phagocytosis of complement and phagocytes, so as to clear various pathogenic microorganisms and damaged tissue cells, and is a sensitive indicator reflecting the inflammatory state of the body. Under normal circumstances, the content of C-reactive protein in human plasma is relatively low, about 10mg/L or less, but if an acute bacterial infection, local ischemia or tissue damage occurs, then the liver cells will synthesize a large number of C-reactive proteins, which will lead to a sharp increase in CRP indicators within a few hours. However, blood CRP has a wide range of applications, and many autoimmune diseases, such as rheumatoid arthritis and systemic lupus erythematosus, can lead to a significant increase in C-reactive protein, so the patient should be assisted by a doctor in conjunction with other medical conditions to make a comprehensive judgment of the disease.