In the early stage of acute pancreatitis, amylase will be abnormally high, clinically amylase includes two categories: one is serum amylase; the other is urinary amylase. In the first few hours of acute pancreatitis, serum amylase will be abnormally high, 24 hours will reach the peak of amylase, and gradually decline, after about 1 week blood amylase will basically drop to normal. However, urinary amylase may be relatively late, reaching a peak in about 24 hours and then gradually returning to normal in about 2 weeks. Patients with acute pancreatitis can be diagnosed early in the course of the disease by checking blood and urine amylase in a simple and convenient way. In addition to relying on the initial screening diagnosis of amylase, acute pancreatitis should be further diagnosed in conjunction with CT of the pancreas, ultrasound and other ancillary impact tests.