Abstract: On the basis of geological survey of the scale of 1:50000 in Xinjiazhuang and Honghuapu sheet in Fengxian area in the west sect of the north Qinling orogenic belt and of achievement of former reserchers,and of comparison of the rock type, petrochemistry,geochemistry of the Danfeng Group, Caotangou Group,author thinks that they belong to calc-alkali series, Danfeng Group is the combination of intermediate rock-basic rock,showing the background of island arc marginal sea; Caotangou Group is the combination of intermediate rock-acid rock,showing the background of move of rift valley of basin after island arc.It provided the new information for discussion the geological evolution of the north Qinling orogenic belt.