The incident happened in the Surma river in Sunamgonj at 9pm after a fire started in the boat's kitchen room.
All but one of the victims was unidentifiable because of the severity of the burns.
Witnesses said the engine-run boat, carrying 100 people including 20 women and children, was going to another district from Sunamgonj at 8pm.
Forty people were injured while a large number of passengers managed to save their lives by jumping out of the burning boat.
Most of the passengers worked as stone collectors in the district.