Abstract: Combining previous data, active fault remote sensing interpretation and geological field survey, we classify the active faults into four classes according the fault activity in city group of central Yunan. They are faults with very high activity rate, faults with high activity rate, faults with moderate activity rate and faults with low activity rate. It shows that there are thirteen main active faults zone in the study area, with an image of "5 longitudinal and 2 lateral" fault zones. The study of the active fault affection on the main project reveals that the active faults are the key geological factor that restricts the layout of the cities and the main projects. The regional crustal stability assessment is calculated by the three factors of faults, rocks and slopes. The result suggests that most areas of the city group of central Yunnan is "unstable", one-third of the city group area is "extremely unstable region", "unstable region" or "sub unstable region".