This study explores the impact of China's higher education expansion, focusing on the regional admission quota system, on intergenerational educational mobility and household investment behavior. We analyze the extent to which these educational expansions reshape family responses across socio-economic groups and the subsequent effects on social mobility disparities. Our theoretical framework posits that increased access to higher education induces heterogeneous household reactions, driven by differing resource availability and socio-economic contexts. As a result, the actual mobility prospects are significantly shaped by the strategies families adopt within the competitive quota-based system. Empirical findings suggest that while the expansion has widened general access, it has not significantly enhanced upward mobility for disadvantaged groups due to their constrained capacity to leverage these opportunities. Conversely, households characterized by higher educational attainment, urban residency, or greater financial resources are better equipped to capitalize on these expanded opportunities, thereby deepening socio-economic inequalities. This analysis highlights the dual nature of regional admission quotas: while intended to promote equity, they often perpetuate educational disparities. Family-level strategies thus emerge as crucial determinants of intergenerational mobility outcomes. These findings highlight the need for targeted policy interventions to mitigate inequities in the quota system by enhancing the capacity of disadvantaged households to benefit from expanded educational opportunities, ultimately fostering equitable outcomes across socio-economic groups.