Dampers are excellent for improving the performance of steel structures and protecting them against earthquakes. The Steel Slit Damper (SSD) is a type of damper designed to be replaced after being damaged under a strong earthquake. Aiming to investigate the effects of the number of blade rows and optimize the length-to-width ratio of blades, seven specimens of identical thickness with one or two rows of blades and three length-to-width ratios were tested and subjected to static cyclic loading. Different parameters, including the force capacity, displacement capacity, effective stiffness, dissipated energy, ductility, and damage indices, were calculated from the experimental results and compared. The results indicate the evident advantage of dampers with two rows of blades in terms of the force capacity, effective stiffness, and absorbed energy, as the highest force capacities corresponding to the two groups exhibited a 61.6 % difference. Furthermore, given the advantage of dampers with two rows of blades and based on the observations, an optimal blade length-to-width ratio (h/b) of 1.58 is recommended to prevent buckling.