The influence of the length of downstream pier wall and the width of the neck pier wall on the failure modes of gate slot, and the design method of shear bearing capacity were studied by static experiments on eight scaled gate slot specimens. The results show that the failure mode of the gate slot changes from the tensile failure of the neck pier wall to the shear failure of the downstream pier wall with decreasing the length of downstream pier wall and increasing the width of neck pier wall. The reliability of the stress graphic reinforcement calculating methods applied to the neck pier wall is verified by comparing calculated and actual reinforcement amount. The limit condition to design the shear bearing capacity of the downstream pier wall is given according to the experiment and finite element calculation results, which provides a reference for the revision of Design Specification for Hydraulic Concrete Structures(DL/T 5057—2009).