The article proposed a novel method to resolve the quantitative application of the SAR images. It is to develop new ground-based spectrum measure instrument to get the normalized radar cross section under the same conditions with the SAR. The ground-based scatterometer uses a pulse as a measuring signal that is matched with the spaceborne SAR. It has more merit than the FM-CW scatterometer in the back scatter measurement. The characters of the pulse ground-based scatterometer are analyzed and the system has been realized.