On March 7, 3-year-old Huanhuan came to my office with her mother. Mom told me anxiously that a week ago, Huanhuan had inserted a button battery into her vagina and now there was a lot of black stuff coming out of her vagina. I asked Huanhuan’s mother how all this happened. She told me that one night a week ago, Huanhuan, who was wearing crotch pants, was playing with a beautiful toy phone in bed alone, while mom and dad were busy with their own business. Mom saw Huanhuan touching her vulva at the time, but thought it couldn’t have been stuffed there by herself, so she thought it had fallen to the floor and didn’t look hard. From March 2, mom found something dirty on Huanhuan’s vulva from time to time and thought it was feces. Later, she found more and more dirty things and they were coming out of her vagina, and that’s when she remembered that a week ago, a battery was missing. I instructed them to go for a pelvic plain film immediately and the x-ray showed a bright round foreign body seen in the pubic symphysis area, which confirmed that the button battery had been inserted into the vagina by Huanhuan and that the black slag was the carbide on the surface of the battery. The mystery was solved and I had to find a way to get it out as soon as possible. After anal examination, I found that the foreign body was deep in the vagina and could not be easily pushed. I first picked out the residue in Huanhuan’s anus to loosen the vaginal wall, and then pushed the foreign body toward the vaginal opening. I repeatedly reassured Huanhuan and her mother for their cooperation, and used small curved vascular pliers to gently and slowly enter the vagina, and after a few tries, I opened the pliers carefully and held the hard object and slowly moved it out. In this way, the battery with a thick layer of black carbon on the surface was invited out of Huanhuan’s vagina. To remove the carbon residue from the vagina, I inserted a catheter into Huanhuan’s vagina and repeatedly flushed the vagina with antiseptic solution until no black pellets came out. I felt relieved to see Huanhuan’s family go home happily. If the battery is left in the vagina for a long time it can erode the vaginal wall and can cause a perforation of the vaginal wall, resulting in urine or feces coming out of the vagina. Severe cases can cause scar or granulation tissue formation, which can affect future fertility. Parents are advised to prevent vaginal foreign bodies in the following ways: 1. Once you find redness and swelling of the vulva, increased discharge, and itching of the vulva, you should seek medical attention and reduce the chances of your child scratching the vulva. 2.Give girls crotch-sealing pants as early as possible to avoid foreign bodies from entering the vagina. 3. Parents should educate their young girls on proper hygiene and guide their curiosity correctly.