Abstract: 6 squat concrete walls and 3 tall concrete walls with construction formwork were tested under simulated seismic loading to investigate the seismic behavior of a new formwork-free composite structure. The damage process and failure mode, the hysteretic characteristic, load carrying capacity and ductility of the walls were studied. A finite element model is proposed for simulating the whole process of nonlinear behaviors of the walls. It is found that the failure process of the concrete walls with construction formwork is similar with that of common concrete walls. All the squat walls are damaged with shear failure modes, while the tall walls are damaged with flexural or bond failure modes. The squat walls with construction formwork have sufficient shear load carrying capacity but their ductility capacity is slightly lower compared to common concrete walls. The tall wall with a flexural failure mode has good ductility capacity while the specimen with a bond failure mode shows poor ductility capacity. The simulated hysteretic behavior, the damage process and failure mode of the specimens are agreed well with experimental results of the walls from their elastic to moderate damage stages.