The Honghuagou ore district and the Lianhuashan ore district in theHonghuagou gold orefield of Chifeng area, Inner Mongolia, have the same lead isotopic composition. The Mesozoic-Cenozoic magmatic and volcanic rocks exhibit very similar lead isotopic composition. The lead isotopic composition of Archaean gneiss and Proterozoic migmatitic granite is also close to that of the above rocks.206Pb/204Pb,207Pb/204Pb and208Pb/204Pb ratios of these rocks are 17.3— 18.1, 15.4—15.7 and 37.2—38.2 respectively; ore lead varies in a wide range, with 206Pb/204Pb,207Pb/204Pband208Pb/204Pbbeing15.37—16.49,14.66—15.89and 35.92—38.48, respectively. The isotopic composition of rock lead is obviously different from that of ore lead, and the arrangement trend of ore lead has nothing to do with the distribution of rock lead, suggesting that the material source of ore lead is not connected with these rocks.This is quite different from character of other gold deposits in the same ore zone. The lead isotopic composition of diopside_bearing plagioclase amphibolite is consistent with or close to that of ore lead, implying the probable existence of genetic connection between them. In the lead isotope evolutionary diagram, ore lead assumes linear arrengement, suggesting that it might be a mixture of two end members, i.e., a mixture of old basement rock lead and old multi-stage evolutionary lead. The end member of the low radiogenic lead reflects the contribution of the Archean basement rocks which are older than rocks of this area to ore_forming materials,whereas the end member of high radiogenic lead represents old multi-stage evolutionary lead,which is the evolutionary product in a highμand high W environment. The source rock of ore lead and gold might be mainly diopside-bearing plagioclase amphibolite within greenstone formation of Archaean besement. Being obviously different from lots of ore deposits in the same ore belt, the Honghuagou gold orefirld has its unique genetic character.