4-year-old boys urinate more (frequent), cloudy urine at night, urine smell, mainly considered with the urinary system inflammation, stone disease and tumor disease and other factors. 1. Inflammation of the urinary system: such as urethritis, cystitis and other diseases, can lead to some inflammatory secretions in the affected skin and mucous membranes, which in turn triggered frequent urination, cloudy urine and odor and other symptoms. 2. Stone disease: such as bladder stones, urethral stones, especially some uric acid stones, can lead to cloudy urine, odor, etc., stone stimulation of the urethral opening, but also triggered by the symptoms of frequent urination. 3. Tumor disease: such as bladder tumors, will form pressure on the urethra and bladder, and some secretions, which will lead to frequent urination, cloudy urine and odor and other symptoms. There may be other reasons why a 4-year-old boy urinates too much, mixed urine at night, and smelly urine, so the patient needs to consult the doctor for examination and treatment as soon as possible.