Abstract: Based on the quantative analysis of faults activity with faults activity velocity, the development episodes, combination characteristics and formation mechanisms of faults in Zhanhua Sag since the Indonesian movement were studied and discussed.The results show that the development of Zhanhua Sag in Mesozoic and Cenozoic was mainly controlled by the convergence of Siberia plate, Yangtze plate and North China plate in Eurasian tectonic system and the activity of Tanlu fault zone of circum-Pacific tectonic system.The development of NW-trending reverse faults in Late Triassic was the local extrusion adjustment result of convergence of North China plate and Yangtze plate.The reversion of NW-trending faults in late Jurassic and Cretaceous was the result of sinistral shear of Tanlu fault zone under the level stretching background caused by the ascending of mantle.which was the result of subduction of Pacific plate.In the interim of Yanshan-Himalayan stage,the transition from sinistral to dextrorotation of Tanlu fault zone resulted in the transition of faults from NW-trending to NE(NEE)-trending in Zhanhua Sag.