The invention relates to an unstacking conveyer device. The unstacking conveyer device comprises a first multi-box conveying roller line and a first single-box conveying roller line, wherein conveying directions of the first multi-box conveying roller line and the first single-box conveying roller line are vertical to each other; an output end of the first multi-box conveying roller line is butted with one side of the first single-box conveying roller line; the output end of the first multi-box conveying roller line is flush with a conveying surface of the first single-box conveying roller line; a butted joint of the first multi-box conveying roller line and the first single-box conveying roller line is of a continuous right-angle bending line structure, and width of the butted part of the first single-box conveying roller line and the first multi-box conveying roller line is sequentially reduced in the conveying direction of the first single-box conveying roller line. The invention further relates to an automatic unstacking system. The automatic unstacking system comprises the unstacking conveyer device and an unstacker. According to the unstacking conveyer device and the automatic unstacking system, boxed goods which are stacked on each layer on a pallet and inconsistent in length and width direction can be separated to be singly transported in the consistent direction.