Business model innovation is a crucial source of long-term competitive advantages for family firms. However, existing research still lacks in-depth exploration of business model innovation in family firms. Based on the special governance characteristics of family firms, this paper proposes the concept of “cross-family ties”. Utilizing the boundary theory, it explores the role of interactions between two groups in business model innovation from experiential dimensions (educational background, industry experience) and identity dimensions (founding veterans, board roles), as well as the boundary constraints of inter-organizational networks. An empirical analysis is conducted using data from 769 family firms in the CPSED II database. The results indicate that cross-family ties in experiential dimensions significantly promote business model innovation, while cross-family ties in identity dimensions have an inhibitory effect on business model innovation. The proportion of institutional investors in the investor network and the industry diversity of the supplier network both positively moderate the aforementioned relationships. This paper expands the contextual scope of business model studies and enriches the discussion on family firm growth from a business model perspective.