The invention discloses an L-shaped screw ship unloader which can improve material taking capacity and efficiency, improve ship unloading capacity, increase the utilization rate, improve the material flow smoothness of a conveying system, improve the load-carrying capacity of a supporting structure, lower ship clearing quantity, lower the energy consumption of the ship unloader and lower the requirement for the manufacturing and mounting accuracy of a vertical screw shaft. The L-shaped screw ship unloader comprises a vertical milling type screw material taking device, a reverse screw spoke middle supporting device, a vertical screw conveyor, a coaxial annular material groove material transferring device, a horizontal screw conveyor, a balance beam, a Y-shaped frame and a supporting frame. The vertical screw conveyor, the horizontal screw conveyor, the balance beam and the Y-shaped frame form a parallel four-connecting-rod mechanism. By means of the scheme, the L-shaped screw ship unloader achieves the purposes of improving the material taking capacity and efficiency, improving the ship unloading capacity, increasing the utilization rate, improving the material flow smoothness of the conveying system, improving the load-carrying capacity of the supporting structure, lowering the ship clearing quantity, lowering the energy consumption of the ship unloader and lowering the requirement for the manufacturing and mounting accuracy of the vertical screw shaft.