It is an urgent question whether and how family force influences entrepreneurship in family business research. From two contradictory perspectives—stewardship and agency theory, this study further extends the research level from family involvement to family relationship, and explores the relationship and mechanism between family cohesion and proactiveness of family business. The empirical result indicates that family cohesion have a positive effect to the proactiveness of family business, while organizational formalization and customer orientation play as the mediating factors. The findings indicate “family harmony” will be the driven force of entrepreneurship which provides the beneficial guidance and operationalized path for enterprise practice.