Potassium citrate is the most commonly used drug to prevent stones. It has been found that the pH value and citric acid value in urine are closely related to the formation of urinary calculi. In acidic urine (pH<5.5), the solubility of uric acid is extremely low, which is easy to cause uric acid stones; In alkaline urine (pH>7), calcium phosphate or magnesium phosphate stones are easily formed. Urinary citric acid is lower than normal in 63% patients with urinary calculi, and potassium citrate can provide a large amount of citric acid to raise the pH value of urine, so it has a very significant therapeutic effect on uric acid calculi, calcium hypocitrate calculi and calcium lithiasis caused by renal tubular poisoning.