Abstract: Remodeling and reconstruction of an ex isting tall building are usually related to seismic retrofit in order to satisfy the demands on new designing code. Structural seismic retrofit should be done according to the actual situation. Based on the main principle of proper stiffness of structure which means avoiding too small or large stiffness and effectively controlling torsion, strategy of partial demolition is suggested for the structures with unreasonable stiffness distribution. Three engineering cases are listed here to demonstrate the necessity of the strategy of demolition for structural retrofit.