The charge sheet was filed against the 52-year-old MLA in the court of District and Sessions Judge E Kharumnuid, who is functioning as the POCSO court judge.
Dorphang, who supports the ruling Congress, and the other accused were charged under provisions of the Protection of Children from Sexual Offences (POCSO) Act.
The sex racket came to light after an employee of a guest house, owned by senior Congress leader and Home Minister H D R Lyngdoh's family, was arrested last month for working as a pimp of the victim girl.
Altogether 16 people were arrested in this case.