Abstract: Demography are determined by the interaction between two section,life-history including birth,death and migration as well as demographic composition including size and structure（sex and age） of population.Demographic processes usually point the variation of these two sections.Demographic variation affects demographic composition（size and structure of population）,social behavior and social kinship in social animals.The paper mainly presents the effects of demographic variation on kinship structure as well as factors determining behavior and kinship structure.