Mineral compositions, clinopyroxene trace-element and Sr-Nd-Hf isotopic   compositions, whole-rock major element and platinum group element (PGE) contents, and  Re-Os isotopes are reported for peridotite xenoliths in the Cenozoic alkali basalts from Yangyuan, Hebei Province (China), in order to constrain the nature of the subcontinental   lithospheric mantle beneath the central part of the North China Craton, and further to   investigate the mechanism of decratonization. The xenoliths mainly consist of spinel lherzolites and minor spinel pyroxenites and spinel harzburgites with equilibration  temperatures of 890-1060 ？C. The olivine in these xenoliths have Mg number (%Fo) ranging  from 88.2 to 91.6. According to the chemical characteristics, two groups of peridotites can be identified, i.e., group 1 are spinel lherzolites and spinel harzburgite that are depleted in Pt, Pd   and Re (i.e., P-PGEs) relative to Os, Ir and Ru (i.e., I-PGEs) and their clinopyroxenes are   depleted in light rare earth elements (LREEs), whereas, Group II are spinel lherzolites that are enriched in P-PGEs relative to I-PGEs and their clinopyroxenes are enriched in LREEs  relative to HREEs. The spinel lherzolites have radiogenic 187Os/188Os ratios ranging from  0.1182 to 0.1262, whereas, the spinel harzburgites have relatively low 187Os/188Os ratios with Proterozoic model ages. Clinopyroxenes in the peridotite xenoliths have variable but  relatively unradiogenic Sr (87Sr/86Sr = 0.7026-0.7046) and radiogenic Nd (？Nd = +2.0 to +14.7)  and Hf (？Hf = +8.8 to +37.9) isotopic compositions. All these geochemical features indicate  that the subcontinental lithospheric mantle beneath Yangyuan had experienced variable   degrees of melt extraction and mantle metasomatism by the silicate melts represented by   spinel pyroxenites. The spinel pyroxenites are enriched in LREEs and P-PGEs relative to  HREEs and I-PGEs. Clinopyroxenes in pyroxenite xenoliths have high 87Sr/86Sr ratios of  0.7054-0.7063, negative ？Nd (-3.4 to -15.8) and ？Hf (-2.0 to -22.0) values, and high 187Os/188Os  ratios of 0.2196-0.3343, indicating that the silicate melts were derived from ancient lower continental crustal materials. Our data suggest that the lithospheric mantle beneath Yangyuan had been metasomatized by silicate melts derived from recycled ancient lower crust, indicating that decratonization of the North China Craton was possibly induced by   delamination of the lower crust and lithospheric mantle. Key Words: decratonization; North China Craton; delamination; Sr-Nd-Hf isotopes