Recently, the population growth and urbanization of the suburban area have been progressing in city in the middle and lower of Huanghe valley. To achieve sustainable city development, overall land use and natural environment control are required. In this research, a new method (Normalized Difference Vegetation Index in Built-up Area: NB) to measure indicator of vegetation activity is developed to evaluate the remaining green tract and the vegetation distribution in built-up area. The NB value is calculated by land use agglomeration (C Index) and NDVI. As a result, the vegetation distribution in built-up area and the situation of urbanization are evaluated overall in the object area.