In this paper, regarding to importance of reduction factor; various different studies have been performed for its calculation and some methods were developed. Lack of this factor for dual frame-panel and panel systems, which used as infilled, in Iranian code, is the major reason for this paper. In this study, seismic behavior of 3, 5 and 10 stories frames with different ratio of infilled panel are investigated subjected to Elcentro, Tabas and Naghan records. Records were selected in the manner that excites all effective natural frequencies of frames. Nonlinearity and energy dissipation due to hysteresis behavior of seismic excitation are fully established. Moreover, structural damping and over-strength and its relevant ductility are investigated. Finally, results obtained by nonlinear static and dynamic analysis show that reduction factor of dual frame-panel are approximately measured between 3 to 6 units.