Abstract: To investigate the elastoplastic characteristics of steel-core aluminum conductor (SCAC) used in transmission lines under cyclic tensile loading, constant amplitude and variable amplitude cyclic loading tests were conducted on 13 sets of JL/G1A-240/30 type SCAC specimens at room temperature. Stress-strain curves of SCAC under cyclic tensile loading were obtained. Defined were key mechanical parameters describing the elastoplastic properties of SCAC, such as elastic modulus during loading, elastic modulus during unloading, keeping strain at maximum load and, residual strain. The influence of load amplitude and cyclic loading mode on elastoplastic properties was studied. The results show that: under constant amplitude cyclic loading conditions, the stress-strain curve exhibits elastoplastic characteristics. The elastic modulus during unloading increases with increasing load amplitude when the load amplitude is within the range of 20%-70% of the ultimate tensile strength. However, when the load amplitude is within the range of 70%-100% of the ultimate tensile strength, the unloading elastic modulus decreases with increasing load amplitude. Under variable amplitude cyclic loading conditions, the overall stress-strain curve exhibits a cyclic staircase pattern. Inserting constant amplitude cycles with amplitudes greater than or equal to 50% of the ultimate tensile strength during variable amplitude cyclic loading can decrease the final elastic modulus of SCAC and increase the final residual strain. The experimental results provide a data support for the disaster prevention and mitigation design of transmission lines.