学校教育机会具有“得到即满足”的充要特性，教育机会供给扩大意味着机会分布不平等下降。受教育年限的复合基尼系数是各机会基尼系数的加权平均。本文以数学推导和数值模拟证明，复合教育基尼系数随教育扩张而下降是其内在的固有性质。利用Barro-Lee世界教育面板数据，本文以实证研究验证了这一基本性质，并建立了教育基尼系数演化形态的解释模型。结果显示，各级教育衔接时序、扩展速率是影响复合教育基尼函数演化的直接因素。

School education has the character of necessity and sufficiency on its “attainment equals satisfaction”; therefore,the expansion of the supply of educational opportunities implies a decrease in the inequality of opportunity distribution. The composite Edu-Gini coefficient for inequality in years of schooling in the population as a whole is a weighted average of the opportunity Gini coefficients. Mathematical derivation and numerical simulations prove that it is an inherent nature of the composite Edu-Gini coefficient that decreases with educational expansion. Drawing on Barro-Lee Educational Attainment Data,this paper validates this fundamental property and develops an explanatory model for the dynamic form of the Edu-Gini. The results show that the dynamic form of Edu-Gini is determined by the cohesive features and the expansion rates of all of educational stages.

本文受国家社科基金重大项目（项目号：19ZDA143）资助。

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