This paper studies the current differences in educational expectations between urban and rural students and explores the mechanism from the individual/family and school/society perspectives. The results show significant differences in expectations between rural and urban junior high school students for going on to higher education. In addition, urban students' educational expectations are higher than that of rural and migrant students. These differences are caused by the students' cognitive ability, family background, and school environment, among which the influence of family background is larger than that of cognitive ability, while the effect of the school's hukou structure is the most important influencing factor. The results suggest that building a desirable school education atmosphere, alleviating hukou segregation in schools, and strengthening the integration of widely diverse school populations are important approaches to promoting educational and social equity in China.