The invention discloses a double-layer large-tonnage elevator car with an adjustable car height and an adjusting method. The double-layer large-tonnage elevator car comprises a car, wherein a middle layer plate is arranged in the car; the car is divided into an upper layer and a lower layer through the middle layer plate; an adjusting system which can drive the middle layer plate to move up and down is arranged above the middle layer plate and composed of an adjusting motor, a guide wheel, a movable pulley block, a fixed pulley block, a drum, an adjusting steel wire rope and a traction steel wire rope; the drum is arranged on an output shaft of the adjusting motor; the adjusting steel wire rope is wound on the movable pulley block and the fixed pulley block; one end of the adjusting steel wire rope is connected with the drum after bypassing the guide wheel; the other end of the adjusting steel wire rope is fixed to the top part of the car; one end of the traction steel wire rope is connected with the movable pulley block; and the other end of the traction steel wire rope is connected with the middle layer plate. The double-layer large-tonnage elevator car and the adjusting method can improve the carrying efficiency of the elevator car, also reduces the well area of hoisting equipment in a mine well and is also convenient in transportation of whole equipment due to the adjustable height.