The pH of urine, the normal range is between 4.5 and 7.9. Urine pH, as one of the elements of routine urine examination, can reflect the ability of the kidneys to regulate the acid-base balance of body fluids and can excrete a large amount of acidic and alkaline substances through urine to maintain the acid-base balance in the body. Nowadays, fixed acids produced by food decomposition need to be excreted daily, so a diet high in protein can produce acidic urine, while urine will be alkaline when eating vegetables containing less fixed acids.