Abstract: Song is one of important secondary sexual characters of birds.The song of male birds is often rich in connotations about species,territory quality,and genetic and physiological states.Thus,according to the song,females can judge the quality of their potential mates,and females preference for complicated songs,in turnover,shapes the song of males,I.e.,the evolution of songs is induced by female choice.The gene of the choice is proposed to be in the W chromosome determining sex in birds.