Most of buried faults on the Chengdu Plain large fault zones composed of multiple branch faults.Radon survey on the eight buried faults on the Chengdu Plain shows multiple peak anomalies with the exception of the Xinjin fault.Activity of the buried faults on the western margin of the Chengdu Plain is stronger than the that of those in the east based on radon anomalies,which indicates that the buried faults on the Chengdu Plain were controlled by the Longmenshan tectonic zone.