The pH of urine is an indicator of the acidity and alkalinity of urine, often affected by factors such as food, water intake medication and retention time of urine specimens, it reflects to some extent the metabolism and kidney function in the body. In general, the pH of human urine is 5.0~7.0, which is acidic. Long-term abnormal urine pH will directly affect the degree of dissolution of substances in the urine and is closely related to the formation of urinary stones. If the urine pH is often high (>7.0), the phosphate crystals in the urine will easily precipitate and form calcium phosphate and ammonium magnesium phosphate stones; conversely, if the urine pH is often low (<5.5), uric acid and cystine in the urine can be converted into a form that is difficult to dissolve, forming uric acid stones or cystine stones. Therefore, frequent checking of urine pH and adjustment of urine pH by diet or medication in patients with urolithiasis can be of positive significance in the prevention and treatment of stones of the above components. Especially when recurrent urinary stones occur and no pathogenic week can be found, frequent measurement of urine H value and adjustment of urine pH accordingly will be useful.