Given the increasing presence of female directors in firms，the roles they play in leading firms’decision-making have attracted extensive attention． However，little is known about why firms choose to appoint female directors at boards． Based on the framework of awareness-motivation-capability( AMC) ，this paper employs fuzzy-set qualitative comparative analysis method． This research investigates the configuration effects of seven congruent factors，including industry female director ratio，female leader，diversification，gender equality culture，regional marketization，financial performance，as well as their causal complex mechanisms on the appointment of female directors． The results suggest that the driving mechanisms behind the presence of a high number of female directors can be categorized into four types: “pressure and atmosphere driver”，“pressure and capability driver”，“pressure and desirability driver”and“desirability and capability driver”． Further， female leaders and industry female director ratio are critical driving factors． There is an asymmetric causal relationship between the mechanisms of high-degree female directors and those of non-high-degree female directors．