Objective To discuss the prevalence of melamine-induced urolithiasis in infants and its development and to formulate more effective diagnosis and treatment. Methods A total of 402 cases of melamine-induced infantile urolithiasis were retrospectively analyzed with basic information, blood, urine, urinary B-mode ultrasonic diagnosis, treatment options and prognosis for infant urolithiasis. Results A total of 402 cases of infants had an excessive melamine milk feeding history, in which there were 9 self-discharged cases. The largest calculus diameter was 4 mm × 5 mm × 6 mm. The smallest calculus diameter was 0.5 mm × 0.5 mm × 1 mm. The average calculus diameter was 1 mm × 2 mm × 2 mm. There were 30 cases of abnormal serum creatinine, 27 of abnormal urea, 2 of abnormal uric acid, and urine occult blood positive for 167 cases. There were 395 cases which were administrated medical treatment; 7 cases were administrated surgical treatment; 6 cases had obstructive renal failure. Conclusion Infants whose age is more than six months but less than 12 months with a history of exposure to melamine have the larger risk of urolithiasis. B-mode ultrasonic diagnosis is practically significant on early screening urolithiasis. It is effective to perform surgical treatment for obstructive renal failure caused by calculus.