Abstract: In order to define the equivalent plastic hinge length of steel reinforced concrete (SRC) frame columns under earthquake, according to the test results of SRC frame columns under low cyclic loading, the top ultimate displacement model of SRC frame columns was obtained through analyzing the failure phenomena and mechanism of SRC columns under earthquake. The plastic rotation angles of each component were established by considering the bending effect in the core area and the strain permeability effect of steel flange. Finally, the formula for calculating the equivalent plastic hinge length of SRC frame columns was obtained by adopting the principle of curvature integral. Meanwhile, the calculated results of the analytical method were compared with experimental results. The results obtained by the calculation formula for the equivalent plastic hinge length proposed agree well with the test results. The research results can provide some theory support for performance-based seismic design and elastic-plastic analysis of SRC structure components.