The object of this paper is to analyze urban-rural income inequality in Beijing.Selecting the time-series data of 1985-2007, the paper analyzes the evolution of urban-rural income inequality in Beijing.Based on the longitudinal data analysis, using two indicators, which are the Gini coefficient reflecting the relative level of income disparity, and the income gap between urban and rural residents, the paper gets some scientific judgments which reflect the state and trends of urban-rural income inequality in Beijing.In the 23 years, the difference between an average annual disposable income of urban residents in Beijing, and an average annual net income of rural residents expands gradually.Studies suggest that changes of urban-rural income inequality in Beijing experience the evolutionary process, which is " low-income-fair-type" ^→ "low-income-unfair type" ^→ " high-income-unfair type".Further analysis is based on the econometrics model, which contains eight indicators of four categories of variables, revealing that there are many elements cause the results of urban-rural income inequality in Beijing, in these elements, three variables impact positively on urban-rural income inequality in Beijing, which are the employment proportion in the secondary and tertiary industries to total employment, the level of urbanization and the dual structure coefficient, and the Government Financial support for agriculture impacts negatively on the urban-rural income inequality.Based on the study above, the paper gets the countermeasures and proposals.It is significant to study the evolution and major effect factor of urban-rural income inequality in Beijing, not only for Beijing itself, but also for the other cities.