Abstract: According to the primary research, the weathering process of Altai Mountain is divided into two stages.Before the Neogene period, chemical weathering was prevailing and formed residiums which are mainly composed of clay. It is important to form the placer.After that period, the environment had changed a great deal and weathering process became complex. both processes have played a different part in forming the placers.Needless to say, the careful investigation on weathering process will be helpful to find out a variety of placers in this region.