A four-year-old child’s eyes often blinking may be caused by eye overstrain, allergic conjunctivitis, pediatric tic disorder and other reasons. 1. Eye fatigue: four-year-olds who watch electronic products for a long time will experience eye fatigue, which may cause the child to blink frequently, accompanied by symptoms of eye swelling and pain. 2. Allergic conjunctivitis: exposure to air pollen, irritating foods and other allergic factors lead to allergic conjunctivitis in four-year-old children, frequent blinking occurs, while the eyes will also appear tearing, photophobia, burning sensation and other symptoms. 3. Pediatric Tourette’s Syndrome: Frequent blinking is also a manifestation of pediatric Tourette’s Syndrome, which is often accompanied by other symptoms such as shrugging of the shoulders and squeezing of the eyes. Four-year-old children inverted eyelashes, nutrient deficiencies and other conditions can also lead to frequent blinking, parents should take their children to the hospital in a timely manner, under the guidance of the doctor to clarify the diagnosis.