The successor selection of family business is facing an increasingly professional trend， but little is known about the mechanism. Therefore， based on the generational differences， it explored how family business owners choose their successors from a cognitive perspective. The longitudinal study of two cases finds that： the key factors that affect the successor selection of different generations of business owners are different， and the intergeneration differences influence the succession decision by shaping the differentiated inherited cognition among different generations of individuals. Therefore， inherited cognition is the intermediate mechanism of generational difference and inheritance decision-making， mainly including familization cognition， professionalism cognition， and open cognition. The cross-generational evolution of inherited cognition is an important reason for the trend of family business professionalism inheritance. It constructs a theoretical framework for the selection of successors for family businesses， reveals the underlying reasons for the decision-making of family business succession， deepens the understanding of the inherited cognition and intergenerational differences in family business， and provides ideas for the follow-up research.