There are many reasons why a three-year-old child has a thick white tongue: first, indigestion, food accumulation caused by eating too much junk food and eating too much, will cause gastrointestinal dysfunction, the tongue appears white and thick, should eat less and more meals, eat more fresh vegetables, fruits, light diet, drink more warm water, can take probiotics to regulate the gastrointestinal, after the gastrointestinal function is regulated, the phenomenon of white and thick tongue will also disappears. Second, the baby often drink milk powder, milk residue on the tongue material, this situation does not need special attention, after a period of time will disappear. Third, may be pathological factors, may baby get thrush, should promptly go to the hospital, under the guidance of the doctor examination and symptomatic treatment, thrush treatment after good white tongue thick phenomenon will slowly become better.