This question is like whether the chicken lays the egg or the egg lays the chicken. However, if we start with the causes of urinary stones, it may help us to understand the relationship between stones and infection. The causes of kidney stones are complex, and the factors involved include external factors, individual factors, urinary system abnormalities, and changes in the composition of urine. Infection, on the other hand, is one of the urinary system abnormalities. The abnormalities of various factors lead to changes in urine, which become stone salt crystals supersaturated, crystallized, then gathered into a mass, and finally retained in the kidney to form stones. Urinary tract infection is the main local factor that induces stone formation. Pus, pus clots, necrotic tissue, and bacterial colonies produced by infection can serve as the cores that constitute stones. As the infected bacteria such as Escherichia coli, Aspergillus, Serratia, Klebsiella, and Bacillus aerogenes, most of them contain ureolytic enzymes, which can generate ammonia from urea in urine and make urine alkaline, thus prompting magnesium ammonium phosphate and carbonate apatite to be in a supersaturated state. In addition, necrotic tissue during infection can also encourage crystals to collect on their surface to form stones. When urinary stones form, they often cause urinary tract obstruction, resulting in poor urinary drainage, which encourages urinary salt precipitation and crystallization. The obstruction also causes poor drainage of urine, which can easily lead to secondary urinary tract infections. Prolonged and repeated urinary tract infections can cause infected urinary stones. The stones themselves are foreign bodies in the urinary tract, which can increase the degree of urinary tract obstruction and the frequency of urinary tract infections. Therefore, urinary tract infections and urinary stones are factors that promote each other in urinary tract diseases. Infection can cause kidney stones, and stone obstruction can aggravate the infection, thus making the stones bigger and bigger and producing a vicious circle. Clinically, we should treat urinary tract infections as early as possible whether urinary stones or urinary tract infections are found first.