The volcanic rocks in the Baitoushan volcano mainly include trachyte, quartz trachyte and comendite. They, together with the underlying Changbaishan basalts, constitute a series from basalt to peralkaline acid rocks and have extreme enrichment in some imcompatible elements (REE, Zr, Nb, Zn, ect.) but are depleted in some of the others (transitional elements, St, Ba ect.). The linear correlation of some pairs of these elements has been observed in the rock series. REE distribution patterns of these rocks display a rightward decline curve with a distinct negative Eu anomaly and gradually rise in their levels and slopes from basalt fo peralkaline acid rocks These features clearly indicate the genetical relationship between the Baitoushan volcanic rocks and underlying basalts. According to the careful study of the features of the trace element models the authors suggest that the fractional crystallization may have played an important role in the origin and evolution of the Baitoushan volcanic rocks. The model of partial melting could not explain the extreme enrichment in some elements but strong depletion in the others in the peralkaline rocks. Mineral phases involving in every stage of the differentiation areestimated by variation of trace elements.