| Based on the calculation of the ratios of employment to population within floating units generated by the software of geographic information system(GIS), the spatial scale and degree of balance are analyzed. With the visualization of change curve and numerical distributions of the cumulative statistical indicators, spatial scales of jobs-housing balance for the employment center and sub-centers, residential communities and other areas in a mega city are obtained. Based on the data of jobs, population, road network in Shanghai, in case of different convergence values, such as 80%, 85% and 95%, the employment center has the largest scale of jobs-housing balance. By 85%, it is about 15 to 25 km for Puxi area, while Pudong area varies from 20 to 28 km. For employment sub-centers, the scales are 4 to 10 km. The balance scales of other zones are determined by the employment center as well as sub-centers. As the distance from the centers increases, it is expanded from 3 km to 8 km, even 17 km. This method could be used to analyze the urban spatial structure and jobs or housing accessibility. By employment and residential commuting distance analysis, it is expected to explain the phenomena and internal causes of jobs-housing mismatch and long-distance commuting.