<p>In this paper, compressive tests of RC columns strengthened with cementitious grout under small eccentric compression were performed to explore the strengthening response. The effects of reinforcement position and thickness on the failure modes, bearing capacity, ductility, and stiffness of the columns were analyzed. Results indicated that the bearing capacity and corresponding deflection of the columns increased gradually with the increase of reinforcement thickness, and the enhancements in bearing capacity of compressive-side strengthened columns were obviously greater than that of the tensile-side strengthened columns. Simultaneously, the ductility coefficients presented a decreasing trend with the increase of reinforcement thickness while the influence of reinforcement position on the ductility coefficients of the columns did not show consistent variations. Moreover, the stiffness degradation rate of the compressive-side strengthened columns was slower than that of tensile-side strengthened columns, and the stiffness degradation rate of the columns decreased with the increase of the reinforcement thickness. Thereafter, a rational calculation method for predicting the bearing capacity of the columns strengthened with cementitious grout under small eccentric compression was proposed.</p>