Abstract: It was presented an experimental research on 18 reinforced concrete columns strengthened by circular steel jacketing subjected to eccentric loading.It was studied that the mechanical properties of the specimens under different eccentricities and initial eccentric loadings.The experimental results showed that the bearing capacity decreased with the increase of the eccentricities,and the original eccentric loading can be neglected.At the same time,A nonlinear analysis program NU was developed to analyze the mechanical property of specimens.The analysis results were compared with the experimental results,and they agree well with each other.Finally,the formula of the eccentricity influence coefficient e was obtained from the induction of parameter analysis result.The calculative results agree well with those of the experiment,and the value of e was discussed.