Abstract: With the advantages of high ductility and energy dissipation capability, the steel plate shear wall with slits becomes a new earthquake-resisting component. Hysteretic behavior of stiffened steel slit wall was analyzed numerically in this paper. Parameters affecting stiffness, strength and energy dissipation capacity of steel slit wall were investigated. Based on the simulated results, some designing suggestions were given. The results show that in order to achieve good anti-seismic performance, the steel slit wall should be designed to undergo full plastic deformation prior to the out-of-plane buckling. It can be achieved by decreasing the ratio of limb width to the wall height, or increasing the ratio of limb height to the wall height. The out-of-plane deformation of steel slit wall changes with the tier number of slitting. With the increment of the stiffeness ratio of stiffeners to infill steel plate, the ductility of steel slit wall was significantly improved. As for the stiffener, it thickness is recommended to be identical to that of the infill steel plate if its buckling is guaranteed to be posterior to the overall buckling of steel slit wall