The Late Triassic Yanzhiba Pluton located in the Northern margin of the Mianxian—Lüeyang Suture, central China.This paper presented the data of occurrence, petrography, zircon UPb chronology and geochemistry ,and genesis of the pluton.The pluton mainly consisted by biotite granite. Zircon LAICPMS UPb dating for the biotite granite yields a weighted mean age of 200±4Ma.They have high SiO2(70.09%～73.35%), alkalis(Na2O +K2O=7.49%～8.59%), Rb,Th,U,K contents and high CaO/Na2O ratios (>0.3), their A/CNK=1.01～1.08 ,σ=2.07～2.62,depletion of Nb,Ta,Ba,Sr,P and Ti. The ∑REE ranges from 129.98×10-6 to 189.97×10-6, slight enrichment of LREE(LREE/HREE=8.00～10.73,(La/Yb)N=8.62～15.68), and significant negative Eu anomalies(δEu =0.41～0.50). In combination with regional geological settings, we suggest that the biotite was formed by partial melting of metasedimentary crust, which was induced by fluids from the lower crust or mantle lithosphere.