Children with a missing piece of hair can be considered to be related to diseases such as baldness or ringworm of the head. 1. Patch baldness: hair loss can be caused by heredity, emotional stress, mental stimulation or immune inflammation, etc. The disease occurs at any age, and there will be a sudden appearance of round or oval well-defined area of hair loss, with smooth skin in the affected area, without scales and scarring. 2. Ringworm of the head: the disease mostly involves children, with scalp and hair of the dermatophyte infection, such as the occurrence of tinea versicolor children, initially there will be a small red pimple, can be gradually expanded to the surrounding area, covered with gray-white scales, the sick hair can be higher than the scalp at 2 ~ 4mm fracture, so it seems to be a piece of the hair is missing. Parents are advised to take their children to the doctor to find out the cause of the missing piece of hair, and then follow the doctor’s instructions to treat the cause and symptoms.