There exist Cd-high areas in alluvial plain of Zhujiang delta, which are distributed in Quaternary marine-continental and continental-marine alternating facies sediments. The characteristics of total Cd content and unstable Cd phase content are obviously different in different sedimentary facies. The total Cd content and unstable Cd phase content tend to decrease gradually from marine-continental alternating facies through continental-marine alternating facies to continental facies. From the surface to the depth, the content ratio of unstable Cd phase is relatively high near the underground water level.