Abstract: The limestone and calcite of Bangpu Mo-Cu polymetallic deposit are surveyed by Carbon，oxygen isotope determination.The results show that there are high carbon (δ¹³C_V-PDB =3.1‰~4.0‰)，oxygen isotope compositions (δ¹⁸O_V-SMOW(5.2‰~12.5‰) and carbonate salinity index value of Z (136.44~141.72) from the early period of limestone，while low carbon(-5.6‰~-3.8‰)，oxygen isotope compositions(1.3‰~5.5‰) and Z value (118.57~120.17) from later period of calcites.δ¹³C_V-PDB-δ¹⁸O_V-SMOW diagram for the carbonate source shows that carbon mainly originates from the alteration of sedimentary carbonate rocks，δ¹³C_V-PDB-δ¹⁸O_V-SMOW diagram for the source of the fluid shows that carbon in the ore-forming fluid mainly comes from magma and dissolution of carbonate rocks which obviously mixed atmospheric precipitation.It is concluded that it is the syngenetic diagenetic environment during the early period while buried mixed water environment during the later period.Carbon in ore-forming fluid was mainly derived from the dissolution of marine carbonate formation，but magmatic rock is also an important factor of carbon formation.Carbon and oxygen isotope results shows that when rainfall intensity increased，δ¹³C_V-PDB shift to a low and negative direction and δ¹⁸O_V-SMOW with a negative xcursion which means isotope excursion.

Key words: Carbon and oxygen isotopes, Dissolution, Mo-Cu polymetallic deposit, Bangpu