Whether or not creatine kinase 311U/L is dangerous cannot be generalized, but should be analyzed on a case-by-case basis, mainly based on the etiology and clinical symptoms to determine whether or not it is dangerous. Normal values of creatine kinase are male: 38～174U/L, female: 26～140U/L (enzyme coupling method, 37℃); male: 15～163U/L, female: 3～135U/L (creatine colorimetric method). Creatine kinase, also known as creatine phosphokinase. Mainly found in the cytoplasm and mitochondria, it is an important kinase directly related to intracellular energy operation, muscle contraction, and ATP regeneration. It is most abundant in skeletal muscle, smooth muscle, and cardiac muscle, followed by brain tissue. Elevation of creatine kinase can be physiologic, with exercise leading to a significant increase in creatine kinase, and the more intense and prolonged the exercise, the more pronounced the increase in creatine kinase. Pathological increase can be seen in myocardial infarction, cerebral infarction, pneumonia, hypothyroidism, various muscle diseases, etc. In this case, we should improve the examination to find out the cause of the disease, and then determine whether it is dangerous or not. If creatine kinase is elevated, it is recommended to go to the hospital in time, complete the examination and follow the doctor’s instructions for treatment.