The agency is looking into a report of an incident where the hands of a 4-year-old student were duct-taped together.
The school says the child was being disruptive during naptime and repeatedly struck staff members.
The boy's parents filed a police complaint, alleging unlawful restraint and then contacted DCFS.
In a statement, the school said it is committed to providing a safe, healthy environment so that children can learn:
"We are thankful to have staff who are dedicated, compassionate and love working with children.
"We have never had a parent or child accuse the school or its employees of any harmful behavior."