The utility model provides an automatic-adjusting mineral separation device, belongs to the technical field of mineral separation equipment, and is used for automatically adjusting the position of a mineral separation plate of a dry type magnetic separator. The technical scheme of the mineral separation device is that the mineral separation device comprises a magnetic material detecting device, a mineral separation baffle plate, a main beam of the mineral separation baffle plate, a stepping motor, a shaft coupler, a lead screw, a worm gear and guide rails, wherein, the magnetic material detecting device is mounted above a waste rock belt; the stepping motor, the shaft coupler, the lead screen and the worm gear are mounted on one side of a mineral separation box; the guide rails are respectively mounted on the two sides of the mineral separation box; the main beam of the mineral separation baffle plate is erected at the upper part of the mineral diving box; a signal output end of the magnetic material detecting device is connected with the stepping motor; the stepping motor is connected with the shaft coupler, the lead screw and the worm gear in sequence; the mineral diving baffle plate is connected with the worm gear; and a road wheel is arranged below the main beam of the mineral separation baffle plate. The mineral separation device can detect the content of magnetic material in waste material, can drive the mineral separation baffle plate to move forward and backward, enables the mineral separation baffle plate to be located in the best mineral separation position, and greatly improves the dry type pre-selection effect of magnetite, and greatly increases the recovery rate of the magnetite.