Abstract: Data of isotope dating for the prolith of orthometamorphic rocks and for the relic zircons of crustal rocks and data of Nd isotope model age for metasedimentary rocks suggest that in the Cathysia Block there is a metamorphic basement mainly consisting of Paleoproterozoic and Mesoproterozoic crust rocks. Cautions have to be taken when citing Sm-Nd isochrons reported in early literatures in China. Reevaluation has to be made to these isochron by isochron criteria that samples of an isochron must have the same origin, the same formation time, closed isotope system since rock formation and large enough variation in parent/daughter ratio values. Since U-Pb ages of relic zircons and Nd isotope model ages of metasedimentary rocks are greater than ages of original rock of the metamorphic rocks, the formers do not reflect deposition age of strata in basement. The U-Pb ages of relic zircons and Nd isotope model ages of metasedimentary rocks suggest that there were recycled Archean crust components in many regions within the Cathysia Block. These recycled Archean crust components can not be regarded as exclusively transported from the remote North China Block. It is worth while to pay more attention on and to study the issue that whether there is Archean terrain in the Cathysia Block.