Adult female Formosan macaques were observed to collect data on the acquisition and stabilization of ranking, troop fission and to compare the female ranking system and nepotistic hierarchy. Behavioral observations were recorded from 1 October 2006 to 30 April 2008. Behavioral sampling methods included scan sampling of macaque troop members, all occurrences sampling of adult females¡¦ affiliative behaviors, and focal animal sampling of aggressive behaviors. In addition, demographic and ranking records were collected from 1998 until 2008. When females attained four years of age, they gained adult female hierarchy, and 88 % (n = 43) of them were middle or low ranking. Individual traits, ageing and mother¡¦s relative rank have significant effects on the ranking of adult females who were 5 to 11 years of age (P < 0.05), and the ranking of 47 % (n = 58) mothers were close to their daughters. When females were 5 to 11 years of age, their relative ranks had positive linear relationships to their mother¡¦s relative rank (P < 0.05). Maternal hierarchy affected the ranking of reminders in troop C, and the dominance matrilineal females stabilized high ranking. But, most subordinate matrilineal females were middle or low ranking. The ranking of 86.4 % (n = 22) of females who immigrated to branch troops was middle or low. Matrilineal members and the ranking before troop fission had effects on the female ranking after troop fission. The ranking of 59.4 % (n = 32) of mothers was higher than that of their daughter. When females reached 9 years old or older while their mothers were alive, mean relative rank of other matrilineal female and mother¡¦s relative rank had significant effects on their ranking (P < 0.05). However, individual traits, mean relative rank of other matrilineal female, ageing, and the number of adult daughters have significant iv effects on female ranking (P < 0.05). When females were 9 to 15 years of age, the rank maintaining ratio of female with mature daughter was 0.82 (¡Ó 0.12), which is significant higher than the ratio of female without mature daughter (P < 0.05). About 50 % (n = 18) of younger sisters outranked their older sisters. The ranking relationships of sister dyads had positive linear relationships (P < 0.05). The proximity index of mother and younger sister was significantly higher than the proximity index of mother and older sister (P < 0.05), but that is independent of whether females outrank their sister or not. Only 4 % (n = 423) female aggression data were recorded that 13 supporters helped attackers to attack victims. The kin and non-kin supporter were 46.1 % and 53.9 % respectively (n = 13). Maternal hierarchy affected the adult female ranking and half of the females outranked their older sisters. However, daughters could also outrank mothers. Therefore, female ranking system of Formosan macaques follows a weakly nepotistic hierarchy. Sterck EHM, Watts DP, vanSchaik CP (1997) The evolution of female social relationships in nonhuman primates. Behav Ecol Sociobio 41:291-309 Su HH (2003) Acquirement of social ranks of females in one group of Taiwanese macaques (Macaca cyclopis) at Fushan Experimental Forest, Taiwan. Am J Phys Anthropol:203-203 Su HH, Birky WA (2007) Within-group female-female agonistic interactions in Taiwanese macaques (Macaca cyclopis). Am J Primatol 69:199-211 Su HH, Lee LL (2001) Food habits of Formosan rock macaques (Macaca cyclopis) in Jentse, northeastern Taiwan, assessed by fecal analysis and behavioral observation. Int J Primatol 22:359-377 Suzuki S, Hill DA, Sprague DS (1998) Intertroop transfer and dominance rank structure of nonnatal male Japanese macaques in Yakushima, Japan. Int J Primatol 19:703-722 Thierry B (1990) Feedback loop between kinship and dominance: the macaque model. J Theor Biol 145:511-521 Wu HY, Lin JF (1992) Life history variables of wild troop of Formosan macaques (Macaca cyclopis) in Kenting, Taiwan. Primates 33:85-97