The Beishacheng intrusion located in the northern margin of the North China Craton, mainly comprising granite porphyry and porphyritic granite, is the primary ore- hosting rock of the Beishacheng Pb—Zn—Ag—Cu deposit. In order to ascertain the genesis of the Beishacheng intrusion and its relationship with the Beishacheng deposit, this paper carried out LA- ICP- MS zircon U- Pb dating, petroleum geochemistry, zircon Lu—Hf isotope and mineral geochemistry studies on the Beishacheng intrusion. Zircon U- Pb dating results indicate that the granite porphyry and porphyritic granite were formed at 276.1 ± 0.6 Ma and 274.9 ± 0.7 Ma, respectively. Both granite porphyry and porphyritic granite are characterized by high silicon, rich alkali, and peraluminous. The rare earth distribution curve is right- leaning, with moderate Eu negative anomaly (0.44 ~ 0.62), enrichment of large ion lithophile elements such as Rb, Th, U, and K, and depletion of high field strength elements such as Nb, Ti, P, and Sr. The granite porphyry and porphyritic granite formed in different evolution degrees of the same magmatic system. The εHf(t) value of the Beishacheng intrusion is distributed between -7.37 and -14.54, and the two- stage Hf isotope model age (TDM2) is from 1763 to 2215Ma, indicating that the Beishacheng intrusion is formed by partial melting of a source dominated by Paleoproterozoic basement. The value of magma oxygen fugacity (NNO) is from -4.78 to -0.11. The crystallization temperature and forming pressure of biotite are 740 ~ 766°C and 280 ~ 441MPa, respectively. The water content of porphyritic granite and granite porphyry range from 11.3% to 13.2% and 8.00% to 8.30%, respectively. The presence of low oxygen fugacity and premature fluid exsolution of the Beishacheng intrusion impedes the enrichment of Pb, Zn, and Cu, which suggests that the Beishacheng intrusion may not be a primary factor in the mineralization process.