Abstract: It is fully explored that the lectotype of top structure and foundation for an outer-jacketing frame storey-adding structural system, through a project of changing two 3-storey brick-concrete buildings(that have been used for over 40 years)into two 7-storey dormitories .The reliable and practical information is also provided for perfecting the design method of the outer-jacketing frame storey-adding structural system according to the experimental study on load bearing characteristics of excavated pedestal piles.