Many people know that the urine triple bile test is used to check for jaundice. However, sometimes it is strange that some patients are already jaundiced, so why do they need a urine triple bile test? Some people are very yellow and the urine test is not always positive. What is going on here? To clarify these questions, we must start from the beginning. The urinary triple bile refers to urinary bilirubin, urobilinogen and urobilin. Jaundice can occur if any of the three processes of bilirubin production, detoxification and excretion in the blood changes, and changes in urinary bile are closely related to changes in bilirubin in the blood. Depending on the nature of the jaundice, the urinary triple bile will change accordingly. Therefore, when jaundice is suspected, a urine triple bile test can be done first. This method is simple, convenient and rapid. The nature of the jaundice can be understood from the changes in the urinary triple bile according to the characteristics of the formation of the urinary triple bile. In hemolytic jaundice, bilirubin is negative and urobilinogen and urobilin are significantly increased; in obstructive jaundice, urinary bilirubin is positive and urobilin and urobilinogen are unchanged or slightly decreased; in hepatocellular jaundice, urinary bilirubin, urobilin and urobilinogen are increased. Although each of the three types of jaundice has its own characteristics, they are interrelated and affect each other, and sometimes cross-positive. Some of the items are also different in the different stages of the disease. Since urobilin is produced by oxidation of urobilinogen in vitro, its changes are consistent with those of urobilinogen, so only two items, urobilirubin and urobilinogen, are often reported in the clinical urinary triple bile test report, but not urobilinogen. The urinary triple bile has some significance for the diagnosis and differentiation of jaundice, but it lacks specificity and precision and should be analyzed clinically in conjunction with symptoms, signs and other tests.