Widespread Late Paleoproterozoic magmatism has been identified in the southern margin of North China Craton (SMNCC) especially in Lesser Qinling Mountains (the Xiaoqinling district). The Xiaohe and Guijiayu granitoids are located in the SMNCC along the Xiaohe fault. A combined LA- ICP- MS zircon U- Pb geochronology, whole- rock geochemistry and Nd—Hf isotope study of the granitoids in Lesser Qinling Mountains provides the insights to discuss the Late Paleoproterozoic crustal and tectonic evolution of SMNCC. From west to east, the crystallization ages of Xiaohe medium—coarse grained monzonitic granite, Xiaohe fine- grained biotite monzonitic granite and Guijiayu granodiorite are 1831±32 Ma, 1860±13 Ma and 1811±10 Ma, respectively. All samples are characterized by high SiO2 (67.4%~76.0%) and high alkali (7.47%~9.33%), plot in the calc- alkali to shoshonite fields. Geochemical characteristics show that XH- 2 and WJY plutons are I- type granite, with collision granite characteristics. XH- 2 pluton, whose forming age is 1831 Ma, has high Sr/Y (26.56~49.52) and (La/Yb)N (31.35~236.71) ratios, Eu negative anomalies (0.42~0.68), indicating that the residue is garnet and plagioclase. The Guijiayu granodiorite has high FeOT/MgO (17.7~29.2) and Ga/Al (2.95~3.17), showing the characteristics of A2- type granite formed in a post- collisional environment, and the crustal thickness is significantly reduced compared to that of 1831 Ma. The zircons have negative εHf(t) (-10.5 to -4.5), and TDM2= 3122~2781 Ma, with a consistent εHf(t) (-7.5 to -4.5) and TDM2 (2888~2667 Ma). It is recognized from Hf and Nd isotopes, the granitoids formed by the partial melting of the crystalline substrate from the Meso- to Neoarchean. This magmatism may be the response of the Lesser Qinling Mountains (Xiaoqinling district) to the 1.85 Ga L?liang Movement, reflecting the crustal evolution process from collisional orogeny to post- orogenic extension.