In order to evaluate the seismic performance of large-rupture-strain fiber reinforced polymer (LRS FRP) confined non-ductile reinforced concrete (RC) square columns under earthquake action, quasi-static experiments were carried out on seven FRP-strengthened RC square columns, including a reference column, a carbon FRP (CFRP)-strengthened column, and five LRS FRP-strengthened columns. The failure modes, seismic performance parameters, and FRP strain of specimens were analyzed, and the effects of FRP types and fiber thicknesses on the failure modes and seismic performance of different specimens were studied. Results show that under axial load and cyclic lateral load, the cover concrete of the reference column in the plastic hinge zone was peeled off and crushed, and the longitudinal bars were severely buckled, while the FRP-strengthened columns did not experience concrete spalling or FRP rupture, indicating that FRP reinforcement changes the failure mode of non-ductile column. Compared with the reference column, the application of FRP significantly improved the ductility and energy dissipation capacity of the RC columns, while the increase in the maximum horizontal bearing capacity was marginal. FRP reinforcement decreased the strain of the longitudinal bars and stirrups, and prevented the buckling of the longitudinal bars. Compared with the CFRP-strengthened column, the large-rupture-strain advantage of LRS FRP was not obvious. The main reason was that the axial load ratio was low and the slenderness ratio was high in this study, so that the compressive area of the FRP confined concrete in the plastic hinge zone was small. Based on the stress-strain model of LRS FRP-confined concrete developed on OpenSees software platform, the experimental results were simulated, and the simulated curve agreed well with the experimental curve, which verified the accuracy and reliability of the model in the seismic analysis of FRP reinforced columns.