Sm Nd and Rb Sr isotope data for amphibolites, greenschists and biotite amphibole plagioclase gneisses from Proterozoic volcano sedimentary sequences and younger granodiorite intrusions in the Bainaimiao Wenduermiao district, Inner Mongolia,P.R.China are presented in the paper. Samples of the Baiyinduxi Group amphibolite yielded a Sm Nd isochron age of 1394±75Ma(2σ). and ε Nd(t)is+7.9±2.1(2σ).This age is interpreted as the time of basaltic eruption, and possibly formation of a primitive mafic crust. Samples of the Bainaimiao Group greenschist gave a Sm Nd isochron age of 1124±57 Ma(2σ)with ε Nd(t)of+0.7±1.1(2σ),which is in agreement with a previously reported U Pb zircon age of 1130 Ma.Samples of the Bainaimiao granodiorite,which intruded into the Bainaimiao greenschist group gave a Sm Nd isochron age of 429±100Ma(2σ)with ε Nd(t)of-2.4±1 7(2σ).This result falls within the metamorphic age range of 362-581 Ma of the Bainaimiao greenschist,determined by mineral K Ar methods. The Rb Sr isotope systems in the same suite of rocks have been strongly disturbed. This observation may be consistent with petrographic characteristics, which indicate that all greenschist, amphibolite and granodiorite have undergone Na or K metasomatism to some extent. The initial ratios of the Nd isotopes suggest that the protoliths of both the Baiyinduxi amphibolite and the Bainaimiao greenschist were derived from a higly depleted mantle source. The ε Nd(t) values of the Bainaimiao granodiorite at 429 Ma indicate that it might have formed by partial melting of the biotite amphibole plagioclase gneiss,greenschist and/or amphibolite. Sm Nd and Rb Sr isotope data for amphibolites, greenschists and biotite amphibole plagioclase gneisses from Proterozoic volcano sedimentary sequences and younger granodiorite intrusions in the Bainaimiao Wenduermiao district, Inner Mongolia, PRChina are presented in the paper. Samples of the Baiyinduxi Group amphibolite yielded a Sm Nd isochron age of 1394 ± 75 Ma (2σ). And ε Nd (t) is + 7.9 ± 2.1 (2σ). This age is interpreted as the time of basaltic eruption, and possibly formation of a primitive mafic crust. Samples of the Bainaimiao Group greenschist gave a Sm Nd isochron age of 1124 ± 57 Ma (2σ) with ε Nd (t) of + 0.7 ± 1.1 (2σ), which is in agreement with a previously reported U Pb zircon age of 1130 Ma.Samples of the Bainaimiao granodiorite, which intruded into the Bainaimiao greenschist group gave a Sm Nd isochron age of 429 ± 100Ma (2σ) with ε Nd (t) of-2.4 ± 1 7 (2σ). This result falls within the metamorphic age range of 362 -581 Ma of the Bainaimiao greenschist, determined by mineral K Ar methods. The Rb Sr isotope systems in the same suite of rocks have been strongly disturbed. This observation may be consistent with petrographic characteristics, which indicates that all greenschist, amphibolite and granodiorite have undergone Na or K metasomatism to some extent. The initial ratios of the Nd isotopes suggest that the protoliths of both the Baiyinduxi amphibolite and the Bainaimiao greenschist were derived from a highly depleted mantle source. The ε Nd (t) values ​​of the Bainaimiao granodiorite at 429 Ma indicate that it might have formed by partial melting of the biotite amphibole plagioclase gneiss, greenschist and / or amphibolite.