The inclusion of coarse aggregates in ultra-high performance concrete （UHPC） can effectively address the issues of high shrinkage and high cost associated with UHPC. This study investigated the bond properties of UHPC with coarse aggregate （UHPC-CA） and steel reinforcement under flexural stress using 12 lap-spliced beam specimens in 4-point bending tests. The distribution pattern of bond stress along the length of the lap splice reinforcement has been obtained by milling a slot on the surface of the steel reinforcement and pasting strain gauges evenly. Key variables studied included coarse aggregate （CA） size， CA content， splice length， and cover depth. The specimens primarily failed in splitting. The results showed that CA affected the bond performance in two ways： it enhanced the mechanical interlock and bonding strength but also increased material inhomogeneity， which may reduce bond quality. Notably， smaller CA （5~10 mm） had a more significant impact than larger CA （10~15 mm）. Increasing CA content to 800 kg/m3 made the bond stress distribution along the splice length more uniform. Extending splice length and increasing cover depth improved bonding strength retention and post-peak performance. A formula was developed to predict splitting bond strength， aligning well with experimental findings.