Abstract: Steel frames have good ductility, but their lateral resistant capacity and stiffness are relatively low. To meet the requirement of structural lateral stiffness and capacity, the frame is usually filled with lateral components, such as steel plate shear walls. The buckling restrained steel plate shear wall (BRSPSW) is an innovative steel plate wall. It never buckles when suffering shear force. It has high lateral resistant capacity, stiffness as well as ductility. The BRSPSW embedded steel frame can greatly improve the lateral stiffness and capacity of the bare frame, and also has excellent ductility. The BRSPSW used in this study is connected to the beams with its top and bottom sides, and partly welded to the columns with its core plate extend end, which can strengthen the shear capacity and stiffness of the beam. This paper theoretically studies the lateral resistant stiffness, yield capacity of the BRSPSW embedded steel frame and their analytical solutions. According to the mechanical model, the lateral displacement induced by shear and bending deformation should be taken into consideration to calculate the structure’s lateral stiffness. The yield capacity of this structure can be divided as shear capacity and bending capacity, in accordance with the yielding pattern of the structure. The comparison between theoretical values and the test data from literature show that they are very close to each other.