Based on the geological survey, trench excavation, drilling exploration and geological dating methods, detailed analysis and comprehensive research were carried on Cangkou fault in Huangdao. Results show that Cangkou fault distribution in Huangdao bay free trade zone, the Wujiazhuang, Changjiang road subdistrict office, Xinzhuang, Gaojiatai, Zhangjiazhuang, Xiaowa, Baiguo village, and into the Yellow Sea near Xinjian village. In Huangdao, Cangkou fault direction is north-east, and tendency is north-west. The length is about 15 km. The width of the fault zone is between 5 and 35 m. Cangkou fault is mainly developed in the Yanshan period granite. The cretaceous strata, modern geomorphology and quaternary deposits are controlled by Cangkou fault. Since the middle Pleistocene, the main movement is right lateral strike slip with thrust movement after multi period movement. The fault zone is interrupted by the fault mud. Bedrock near fault zone is broken. For security reasons, the authors suggest considering 14 m width as the safety distance of the Cangkou fault in Huangdao. The research of the spatial distribution and the present activity of Cangkou fault in Huangdao has important significance to the reasonable planning, comprehensive development and utilization of land, the seismic geological disaster assess-ment of engineering in the future.