This study focuses on the family background study of high school students who come from 8 urban high schools of 6 provinces and the students’ family background survey in a key high school in the past 30 years，to reveal the education chance equality and changes in the high school. The study shows the government officials，the business managers，the technical personnel and other classes that are the traditional and new advantaged group got the more opportunities to enter the key high school，while the opportunity of receiving high quality high school education for those disadvantaged groups are diminishing，especially for the children of ordinary workers，and farmers. This result shows that the education equality task in high school education is still very hard.