When many patients go to the hospital, the doctor will ask for a urinalysis to assist in the examination and diagnosis of certain diseases. As one of the “three routine” items in clinical medicine (the other two are blood and stool routine), urinalysis is more economical and faster than other tests, and has important reference value for the diagnosis and treatment of many diseases. In general, the color of urine is light yellow, but if you drink little water or sweat a lot, it may be dark yellow. If you take certain medications or eat certain foods, it is possible to cause a change in urine color. In pathological cases, if the color of urine becomes red, it may be due to inflammation of the urinary system, stones, tumors, tuberculosis, trauma, or blood system diseases. If the urine is yellow, it may be bilirubinuria, which is considered to be due to cholestatic jaundice, hepatocellular jaundice. Urine transparency should be clear, if it is cloudy, it suggests a high possibility of lesions. If the urine contains a lot of crystals, blood, pus and celiac disease, it becomes cloudy or foamy. Urine pH is around 6.5, too high or too low, suggesting the possibility of pathological diseases, especially certain kidney or metabolic diseases are likely. Red blood cells, protein, ;sugar, ketone bodies, urobilinogen, bilirubin, etc. are generally trace or absent. An increase in the above components in urine can occur with urinary stones, nephritis, diabetes mellitus, and biliary tract disease, causing changes in appearance and improving reference for the clinician. In addition, attention needs to be paid to maintaining local hygiene when retaining urine, and generally retaining mid-stage urine to prevent inaccurate results due to contamination. Female patients should generally not take urine for examination during menstruation. A few milliliters of urine can reveal or detect many diseases and provide an important reference for the physician’s diagnosis and treatment.