Abstract: To study the shear performance of Fiber-Reinforced Polymer (FRP)-Ultra High Performance Concrete (UHPC) composite beams,the FRP-UHPC composite beams with FRP shear keys (FSKs) were investigated through four-point bending tests and refined Finite Element (FE) analysis.The concrete damaged plasticity model and the Puck failure criterion were used to simulate the progressive damage of concrete and FRP profiles,respectively.The mechanical behavior of the interface was simulated using a bi-linear cohesive zone model.The comparison between the FE analysis and experimental results demonstrates a good agreement.Based on the validated model,a parametric analysis was conducted on the shear performance of FRP-UHPC composite beam with FSKs,focusing on the effect of parameters such as concrete slab strength,height and width,FRP web shear strength,shear modulus,height and thickness,and FSK spacing.The results indicate that the local slip of the composite interface with FSK is much smaller than that of without FSK,and the maximum local slip is less than 4mm,which verifies that FSK has good interfacial shear resistance.Increasing the strength and section size of the concrete slab can improve the shear stiffness and the shear capacity of the composite beam.Besides,the use of UHPC for concrete slabs can also effectively inhibit interface slip.Increasing the shear strength and thickness of FRP web can improve the shear strength and deformation,the failure mode changes from shear failure to bending failure.The reduction of FSK spacing can effectively enhance the shear performance of the interface,thereby improving the combined effect of the composite beam and increasing its bearing capacity and deformation.