Drawing upon data from marriage registration，this paper examines recent trends in the average age at first marriage of newly married population in the past eight years in Beijing．The male's average age at first marriage stood at 28．05 years and stayed rather stable，while the female' s averaged at 26．21 years but shows a significant increasing trend．Analysis by migration type demonstrates that the average age at first marriage of migrants ( hukou in Beijing but native place not in Beijing) is significantly higher than the average level of all，which pushes up the general average age at first marriage． The average age of newly married male floating population ( hukou not in Beijing) is similar to that of the migrants and also lifts up the general average marriage age，but the impact of female floating population is opposite．Moreover，because of the gender difference in terms of the proportion of cross household registration intermarriage，female local population suffers to certain extent some marriage squeeze．Under the influence of marriage gradient and matching customs of“older husband with younger wife”，the average age at first marriage of female local population in Beijing may be further delayed in the long run．