In order to better diagnose and treat urolithiasis, the necessary classification of urinary stones is needed. The main classification methods are: according to the cause of urinary stone formation, stones can be divided into two categories: primary stones and secondary stones. Primary stones are generally those stones for which no clear abnormality can be found on various tests due to the long duration of the disease, the absence of clear symptoms in the patient, and the general inability to find a clear cause. In the case of physical examination, many primary stones are detected by ultrasound. Secondary stones are stones secondary to other diseases, such as obstruction, infection, foreign bodies, malformations, etc. According to the location of urinary stones, stones can be divided into two categories: upper urinary tract stones and lower urinary tract stones. Upper urinary tract stones include kidney stones and ureteral stones, while lower urinary tract stones include bladder stones and urethral stones. According to the composition of urinary stones, stones can be classified into calcium-containing stones (such as calcium oxalate, calcium phosphate, calcium carbonate, etc.), infected stones (the main components are ammonium magnesium phosphate and hydroxyapatite), uric acid stones (such as uric acid and ammonium urate), cystine stones and stones of other rare components, etc. According to the purity of the stones, they can be divided into simple stones and mixed stones. The former contains only one component or mostly one component, but in fact true simple stones are rare; the latter are composed of multiple components. According to the metabolic activity of urinary stones, stones can be divided into two categories: metabolically active stones and metabolically inactive stones.