To study the bonding behaviors of the interface between steel rebar and ultra-high performance concrete (UHPC) for the thin and light reinforced UHPC members, several pull-out tests of reinforced UHPC specimens with different design variables, such as the diameter and cover thickness of steel rebar, and bonding length, were tested in this paper, and their influences of design variables on the bonding properties of the interface between steel rebar and UHPC are investigated. Based on the test results, the effect of each design parameter on the failure types, bond stress-slip curves, bond anchoring strength, and corresponding slip of the reinforced UHPC specimens is analyzed. The obtained results show that the changes in the rebar diameter, bonding length, and cover thickness have a great influence on the bonding behaviors of the interface between the steel rebar and UHPC. The ultimate bond strength and corresponding slip increase with the decrease in bond length, while it first increases and then decreases with the increase of the rebar diameter. The ultimate bond strength decreases with a reducing rebar cover thickness, while the corresponding slip increases. When the diameter is 12 mm and 16 mm, the cover thickness and the bonding anchor length of steel rebar should not be less than 1.5 times and 4 times of rebar diameter, respectively, while the bonding anchor length of the steel bar with a diameter of 8 mm should not be less than 3.5 times of the diameter. The calculation formulas of ultimate bond strength and critical anchorage length for the interface of reinforced UHPC are derived from mathematical statistics method, and they agree well with the test results.