A piece picking system, comprising at least one main conveyor unit and a plurality of sorting modules, wherein the at least one main conveyor unit and the plurality of sorting modules are arranged crosswise in a matrix, and the at least one main conveyor unit is located above or below the plurality of sorting modules; each of the plurality of sorting modules comprises a sorting track; a plurality of picking stations are arranged at a side of the at least one main conveyor unit, and are adjacent to the each of the plurality of sorting modules; the at least one main conveyor unit is configured to convey a first container carrying an item to be picked; each of the plurality of picking stations is configured to pick the item in a required quantity from the first container conveyed by the at least one main conveyor unit according to an order requirement; and the each of the plurality of sorting modules is configured to sort the item picked by an adjacent picking station; the at least one main conveyor unit comprising at least one main conveyor line and the at least one main conveyor line and the sorting tracks are arranged crosswise in a matrix; the each of the plurality of picking stations is provided at a corresponding crossing of the at least one main conveyor line and the sorting tracks; chararacterized in that the at least one main conveyor unit comprises a staging line; the staging line is located at one or two sides of the at least one main conveyor line; the piece picking system being configured such that the first container is transferred to the staging line for the each of the plurality of picking stations to pick the item in the required quantity; and that a second container carrying a remaining item after picking is staged on the staging line or transferred to the at least one main conveyor line to be taken away; the at least one main conveyor unit is provided with a lateral transfer device, and the lateral transfer device is configured to transfer the first container and the second container between the at least one main conveyor line and the staging line; wherein the piece picking system further comprises an auxiliary conveyor line, the auxiliary conveyor line is configured to carry an emptied container away from the picking station. the at least one main conveyor unit comprises a staging line; the staging line is located at one or two sides of the at least one main conveyor line; the piece picking system being configured such that the first container is transferred to the staging line for the each of the plurality of picking stations to pick the item in the required quantity; and that a second container carrying a remaining item after picking is staged on the staging line or transferred to the at least one main conveyor line to be taken away; the at least one main conveyor unit is provided with a lateral transfer device, and the lateral transfer device is configured to transfer the first container and the second container between the at least one main conveyor line and the staging line; wherein the piece picking system further comprises an auxiliary conveyor line, the auxiliary conveyor line is configured to carry an emptied container away from the picking station.