The mother rock forming rare-earth placer is mixed rock of Bacun Guorp of Cam-brian system or mixed granite of Caledonian period. The sandridge placers are formed by redeposited alluvial sediments. The dominant wind is easterlies in this area,so that the wave and tidal current,the Grains of placer move from east to west. Therefore,in the west part of sandridge,the placer grains are more rich than the east part. The Quater-nary stratigraphy can be divided into five formations, by comparing the 5 formations with the contents of placers are shown, in which the upper Pleistocene (Shawei formation) is the richest with the greatest thickness,the middle Holocene lower(Nan-shahai formation) is the next,followed by the Upper Holocene (Guanghai formation). There are two inclined beds of poor placers with regressive facies between the three rich beds. Becoming richer from up to low is the vertical minerogenic regularity.