Abstract:Based on the data of CSI 300 Constituent Stocks Listed Companies, an empirical research is conducted to test the influence of the board taskrelated faultlines on firm value and the mediating effect of board effort level. The empirical result shows that the board taskrelated faultlines has negative effect on board effort level and firm value, and that board effort level acts as a partial mediator in the relationship between board taskedrelated faultlines and firm value. Further, the board group faultlines has indirect influence on firm value through board effort level.