The Caojiazhai Cemetery is a civilian cemetery of the Qing Dynasty located in Xixian New Area, Shaanxi. In this paper, the human bones unearthed from the Caojiazhai Cemetery were analyzed by paleodemography; combined with historical documents, the population structure and age distribution of the residents in the Qing dynasty in the Caojiazhai Cemetery were studied, and the reason for its formation and the revealed family structure and marriage form of the civilian class in Qing Dynasty were explored. The results have shown that the sex ratio of residents in the Caojiazhai Cemetery is 117.5, and the quantity of men is far more than that of women; the higher sex ratio of residents may be related to the “Drowning Baby Girls” custom that prevailed in the Qing Dynasty. The average age of death for male residents in Caojiazhai was 44.41 years old, and the average age of death for female residents in Caojiazhai was 38.42 years old. Their life expectancy was much lower than that of the Qing gentry population in the literature and epitaph records, which reflected the living conditions of the civilian class in Guanzhong area in the Qing Dynasty. The peak of their deaths was in the middle age, but the fertility behavior made the death rate of women in the middle age more than twice that of men, and more male residents lived to their old age, which indicated that men have a relatively longer lifespan in individuals. By comparing the population’s age distribution of death from the Neolithic Age to the Ming and Qing Dynasties in Guanzhong area, the mortality rate of the residents of Caojiazhai in the Qing Dynasty was still the lowest in the youth and the middle of life, and more people lived to their old age, which showed that human life span gradually increased with the development of social productivity and the improvement of medical conditions. The burial methods of single, double, and multiple persons, and relocation behaviors of the second burial and skeletal disturbance in Caojiazhai Cemetery all reflected the form of monogamous and polygamous marriages in the Qing Dynasty. As a civilian class, their behavior of accepting concubines was limited by financial resources and was not common. Small family was the mainstream form of rural families in Shaanxi during the Qing Dynasty.