Education serves as a critical driver for class mobility and human capital accumulation, particularly in countries with pronounced socio-economic stratification. This study investigates the heterogeneity and temporal evolution of educational opportunity inequality in China, focusing on the urban-rural dual structure, gender disparities, and uneven regional development. The study measures how environmental factors, including household registration, income, and regional resource distribution, contribute to educational disparity using micro-level data and a parametric methodology in conjunction with the Shapley value decomposition method. Multiple intelligence theory and discrete inequality indicators, including the Theil index and Gini coefficient, are employed to measure disparities across different education stages. Empirical analysis reveals that although overall educational inequality has declined due to policy interventions, the relative share of inequality stemming from environmental factors has risen since the 1960s. This indicates that exogenous conditions, rather than individual effort, increasingly determine educational outcomes. Additionally, algorithmic optimization and robustness tests enhance the reliability of the measurement framework.