An improved double-shear pull testing method was proposed with the improvements of loading fixture, fastening, and clamping devices to discuss the bond behavior of fully bonded carbon fiber reinforced polymer (CFRP)-concrete interfaces. The improvements provided a stable CFRP-debonding process due to the anchorage effect of the peripheral fasteners . Using the improved method, double-shear experiments with fully bonded CFRP (bond width ratio β = 1) could be carried out successfully, and the bond-slip relationships of the interface on any cross-sections (lines) of the fully bonded CFRP could be obtained. All of the valid experimental data show a better linear relationship between maximum bond stress τ max and corresponding slip s 0 , and a simple bond-slip model was proposed based on Popovics's equation. • A new double shear test for fully-bonded FRP-concrete interface with the improved specimen and devices was proposed. • The failure mode of specimens can be ensured as debonding failure of FRP-concrete interface by using the testing method. • A simple bond-slip model was proposed with the experimental data based on Popovics's equation.