The invention discloses an intellectualized method for preparing purified indigo. A distillation extraction device is used and comprises a reaction machine body and a distillation machine body arranged on the end face of the top of the reaction machine body, a reaction cavity with an upward opening is formed in the reaction machine body, and a distillation cavity communicated with the reaction cavity is formed in the distillation machine body; a partition plate is arranged at the top of the reaction cavity, symmetric first guide slide grooves located at the two ends of the distillation cavityare formed in the distillation machine body, and second guide slide grooves are formed and communicated between the first guide slide groove and the distillation cavity; an opening runs through the interior of the wall of the distillation cavity, a power machine body is arranged at the top of the distillation machine body, and a first cavity is formed in the power machine body; a first motor is embedded in the inner wall of the top of the first cavity, and a first belt wheel is in power connection with the tail end of the bottom of the first motor.