Abstract: After the appearance of Wenchuan M8.0 earthquake in central-northern segment of the Longmen Shan in 5th anniversary, Lushan earthquake in the southern segment of Longmen Shan appeared on April 20, 2013. Based on the basic characteristics of Lushan earthquake and the tectonic，geomorphic，water system，the distribution of the gravity anomaly characteristics of Longmen Shan Fault zone to analyze the regional geological background of Lushan earthquake and explore the relationship between the Lushan earthquake and wenchuan earthquake, we draw the following conclusions: ① the Lushan Earthquake is not the aftershocks of Wenchuan Earthquake ,they are two independent earthquake and has some relevance, the appearance of Wenchuan earthquake could promote the Lushan earthquake; ② the obduction of lower crustal flow may be the common genetic mechanism of the Lushan Earthquake and Wenchuan Earthquake, which can well explain the empty area between them; ③ there are many faults and folds in the front of the southern segment of Longmen Shan, to some extent, which can release the stress from the northwest to the southeast in this zone. Therefore, the southern segment of Longmen Shan do not have the tectonic background of the Wenchuan Earthquake.

Key words: Lushan earthquake, Wenchuan earthquake, Longmen Shan, segmentation