Regression-discontinuity is used to analyze metropolitan circles of Beijing, Tianjin, Hebei, the Yangtze River Delta and the Pearl River Delta, and the results show that the urbanization level in the areas inside metropolitan circles is 1~2 percent higher than that of the areas outside the metropolitan circles and that the metropolitan circles have no direct impact on the variances influencing wage disparity such as farmland, education level, financial development level and so on. Two-Stage Least Square Estimation is further used to study the impact of urbanization level due to metropolitan circles formation on urban-rural wage inequality, and the results indicate that the increase of urbanization level narrows urban-rural wage inequality. Some institutional barriers resulting from urban-rural dual economy and the imbalance of urban-rural financial development are the main reason for current enlargement of wage inequality, thus, the institutional barriers blocking the flowing of labors between urban and rural areas should be rapidly eliminated, and rural financial system should be continuously perfected.