Assess the efficacy and safety of potassium citrate extended-release tablets on Urolithiasis formation or recurrence.

This study takes "Rate of stone recurrence" as primary outcome measure, by random, blank control, and multicenter clinical trial design method, assess the efficacy and safety of potassium citrate extended-release tablets on Urolithiasis formation or recurrence, provide evidence for drug re-registration, and observe its efficacy on Urinary calculi such as renal tubular acidosis with calcium stone, and uric acid stones with or without calcium stone, urinary tract stone of effectiveness.

Inclusion Criteria:

• Patients with upper urinary tract calculi surgery and/or ESWL within 3 months；
• Stone free or had residual stone fragments with a less than 4 mm diamete；
• 18-70 years of age; the gender is not limited；
• Agree to take effective contraceptive measures during the study period, and female of childbearing age whose pregnancy test is negative；
• Subjects with no mental illness and language dysfunction, can understand the situation of the study and have signed informed consent.

Exclusion Criteria:

• Patients with infectious stones, medical stones and urinary tract obstruction；
• Patients with hyperkalemia (K+>5.5mmol/L) (or patients with factors or disease that can cause hyperkalemia), because the further increase in blood potassium can lead to cardiac arrest. These factors include disease or strenuous exercise, chronic renal failure, uncontrolled diabetes, acute dehydration, excessive, adrenal insufficiency, extensive tissue failure. Patients who takes potassium sparing diuretics (such as triamterene, spironolactone, amiloride)；
• Patients with gastrointestinal disorders, such as peptic ulcer, severe vomiting, diarrhea, delayed gastric emptying, intestinal obstruction, etc.；
• Combined with cardiovascular, liver, kidney, hematopoietic system, such as severe primary disease, or known to affect the survival of serious diseases (such as cancer or AIDS), or patients with with disabilities mentally or legally；
• Patients with renal insufficiency (1.2 times the upper limit of the normal value of serum creatinine and urea nitrogen)；
• The recent (within 6 months) with family planners；
• Allergic to this product；
• To participate in other clinical trials in the past three months.