Abstract: The Zhu Ⅲ Depression in the Pearl River Mouth Basin is a halfgraben-like depression with well-developed fault system.Formation and evolution of the depression have been controlled by faults.Controlled by main faults,the depression can be divided into 9 tectonic units such as the Wenchang A Sag,among which the Wenchang A,B and C Sags are petroleum generative.Faults in the depression are mainly NEE oriented.According to combination of the main and the secondary faults,there are 4 combination styles in plane,including parallel,en echelon,broom-like and ‘Y'-like.In section,there are also 4 combination styles,including homoclinal ‘Y'-like,reverse ‘Y'-like,complex ‘Y'-like and accor-dant fault step.Faults control source rock distribution,reservoir generation and distribution as well as petroleum generation and migration.The controlling effects may be favorable or unfavorable.The main faults,especially the ‘Y'-like faults generative region,are the key targets for petroleum exploration in the Zhu Ⅲ Depression.Uplifts along the edge of the depression which are far away from oil generation center and blocked by faults should be taken as long-term targets.