Abstract: The Kainankang Formation or Kainankang gneiss in regional metamorphic rocks of the Tananao Group in eastern Taiwan Province is considered as the horizon of this group. The Chipan gneiss is a typical component of the Kainankang gneiss. There is much dispute over its protolith, origin and age. The protolith of the Chipan gneiss should be monzogranite and the formation ages of crystalline zircon are （259±6） Ma, （1 295±8） Ma and （1 589±8） Ma respectively. According to these ages combined with the macroscopic geological features, the age of the rock body is considered to be Permian, and again according to the polymictic conglomerate of the Chihuichiao in the Tailuku area, it is inferred that there existed the Hercynian Dongwu movement in eastern Taiwan.