Since in new-technology buildings, speed and quality are two important factors in selecting the type of structures, the industrial implementation hasreceived much attention. The LSF structures are made of cold formed steel and due to the high strength-to-weight ratio, they have been developed rapidly. LSF combined with steel frame as a dual system could reduce the construction limits like constructing stairs. It is also effective in ductility of structures. In the present study, the required design parameters like ductility factor and behavior factor has been investigated by using nonlinear static analysis. Based on pushover results, three parameters have been defined in behavior factors i.e. ductility, over-strength and ductility reduction factor. Based on the results obtained in this research, in the two-story structure, the optimized performance of the dual system has been achieved when stiffness of steel part is more than the stiffness of LSF part. This results is an increase in lateral capacity and ductility. It is suggested that the difference between the stiffness of steel part and LSF part to be selected less than 5%. In addition, it is recommended that in three-, four- and five-story buildings, to design the combinational system of LSF and steel frame in a way that the stiffness of the steel frame be less about 10% lesser than stiffness of the LSF parts.In this condition, this dual system has a good performance in strength and capacity and performance of ductility is acceptable.