Chemical compositions of the coexistent mineral phases (olivine, spinet, clinopyroxene and orthopyroxene) in the spinet lherzolite and harzburgite xenoliths from Fanshan and Panshishan,Jiangsu Province, were determined by the electron and proton microprobe. The equilibrium oxygen fugacities were calculated by two oxygen geobarometers calibrated by Ballhaus et al.(1991) and Bryndzia and Wood (1990 ) respectively. The difference between the two results is lower than 0. 5 log(fO2)`FMQ unit. The oxygen fugacities of the spinet peridotite zone in subcontinental lithospheric mantle beneath Eastern Yangtze Block are flog( fO2)FMQ=-2.0-0. 5, the typical values for subcontinental lithospheric mantle worldwide. The accurate Fe3+/Fe2+ atio of spinet is a key factor for the calculation of oxygen fugacity.