Joints between segments in cantilever casting concrete bridges require special attention in design and construction. These joints introduce discontinuity in the bridge; furthermore weaken the connection stiffness and strength of corresponding section, which may lead to excessive downwarping of bridge. Experiments were conducted to assess the shear stiffness of segmental joints section. The parameters studied included monolithic non-joints, joints roughened, joints roughened with shear-key. It was found that the shear stiffness of jointed section is largely lower than that of non-jointed section; however, the shear-key can effectively enhance the shear strength and especially shear stiffness of the joints section. Measures are proposed for shear-key design, and may provide a rational basis for the design of cantilever casting concrete bridges.