The purpose of urine culture is to select the cleanest urine in a section of urination for culture, the accuracy of the test results is higher, the possibility of contamination by exogenous sources is smaller, and the reference significance of the results is greater. During a urination, the urine at the beginning of the urination and the urine at the end of the urination may be contaminated by miscellaneous bacteria from the urethral orifice, male foreskin or vulva, but the urine in the middle section is least likely to be contaminated by miscellaneous bacteria because of the continuous flushing of urine, and the pathogenic bacteria in the urethra or vulva will not multiply during the culture process, leading to deviations in the test results, because urine culture is the most accurate way to diagnose Urine culture is the most accurate basis for the diagnosis of urinary tract infections. The urine culture results need to be tested for drug sensitivity, and if the miscellaneous bacteria multiply and a wrong diagnosis is made, then after the urine culture the clinician will have to use the wrong drug for treatment. Therefore, the purpose is to select a clean section of urine for culture as much as possible, to prevent contamination by miscellaneous bacteria and to improve the accuracy of the test.