Abstract: Alluvial gold placers are the most important and worthful gold placers at Altai Mountain. Large scale, high grade, ease to mining are the characters of the alluvial gold placers. After researched a large numbers of the alluvial gold placers at Altai Mountain, this paper discusses its mineralization laws of the Altai Mountain, they are related to：1. the placer-golds enrichment and their sources, 2. placer-gold containing layer belonging to the special layer, 3. the sediment of the placer-gold and the rocks of the river bed, 4. the sediment of the placer-golds and the shape of the river valley, 5 . the result of a gold-containing branch river joins the main river, 6 . the stablity of the river-bed being benefit to the mineralization, 7. the longer time to form, the bigger of the placer-gold-grain, 8. the key to form the high-grade, large scale placer being pile up the all adventageous factors above.