The invention provides an automatic brick-stacking assembly line. According to the automatic brick-stacking assembly line, the placement density of bricks can be adjusted, the posture of the bricks can be adjusted, the brick-stacking direction can be adjusted, the automation degree can be obviously improved, and the cost can be lowered. The automatic brick-stacking assembly line is composed of a low density conveying belt, a high density conveying belt, a stacking manipulator and a tray, the low density conveying belt and the high density conveying belt are respectively composed of a driving wheel, a driven wheel and a plurality of belt bodies winding around the driving wheel and the driven wheel, the belt bodies of each of the low density conveying belt and the high density conveying belt are arranged at intervals, the belt bodies of the low density conveying belt and the belt bodies of the high density conveying belt are arranged alternately at the joint of the two conveying belts, and the conveying speed of the high density conveying belt is smaller than the conveying speed of the low density conveying belt. The low density conveying belt comprises a brick overturning mechanism, the brick overturning mechanism comprises a rotating shaft and two or more overturning arms arranged on the rotating shaft in a protruding mode, and opposite side surfaces of every two adjacent overturning arms form a brick clamping part with the included angle being 90 degrees. The tray can rotate.