From the perspective of the intergenerational accumulation of advantages and disadvantages, this study builds a three-dimensional measurement of employment quality from income, social insurance and to job satisfaction to explore the cross-sectional and dynamic effects of intergenerational educational mobility on employment quality of employees and its mechanism. Using the data of China Family Panel Survey (CFPS) from 2014 to 2018, the study distinguishes four groups of intergenerational educational mobility types with the relative educational level measuring method and the object groups include immobile high, mobile up, mobile down and immobile low. It is found that the immobile high group with the richest generational accumulations of advantages have the best employment quality. Mobile up group have the second order, then the mobile down group and the immobile low group have the lowest employment quality. Immobile low and mobile down groups have more accumulated disadvantages in younger cohorts than in older ones. The mechanism analysis shows that lack of contract leads to the disadvantages of mobile down and immobile low groups while the higher over-education rate results in the disadvantage of mobile high group. Therefore, promoting substantive upward mobility in education can not only promote educational equity, but also achieve higher-quality employment development as an important way.