On the basis of an overall analysis and study of mercury--injection data，thin sections，SEM，cast sections and diagram analysis of the target intervals of．main coring wells in the study area，the paper reveals pore structure heterogeneity of fluvial facies reservoirs of the upper member ofthe Guantao Formation in the west of the seventh district of the Gudong oilfield．The pore typesof reservoirs of the upper member of the Guantao Formation are mainly primary pores．The het—erogeneity of pore structure is obvious．There is obvious difference in pore structure characteristicsof sedimentary microfacies，and,their degrees of heterogeneity are also different．From the channelbar．point bar and channel filling to channel border，the radius of the pore throats becomes small-er successively，the pore structure becomes more complicated and the degree of heterogeneity isincreased．