Detailed studies on trace elements in ores, walirocks of intrusion and orebodies in Yinshan depositshow that ∑REE increased in all samples except in those close to the intrusion and orebodies. Altered wallrocks with lower w(LREE)/w(HREE) ratios were depleted in Eu, as compared with their fresh counterparts. The calculation results suggest that less than 31% of the increment of REE might have been caused by mass transfer and that the remaining percentage might have been responsible for the addition of REE into the rock from hydrothermal fluid that caused rock alteration. The acting hydrothermai fluid was characterized by low w(LREE)/w(HREE) ratio with a strong positive anomaly. The reductive state of the hydrothermai fluid resulted in the loss of Eu by reducing Eu3+ into more mobile Eu2+. In other trace elements, Hf, Th, U, V, Cr, Co, Nb, Mo, Ta, Zr and Rb show immobility,Y, Sc and Sr were carried off while Cu, Pb, Zn, Ag, Sn and Ba were introduced into altered wallrocks by hydrothermal fluid during hydrothermal alteration.``