Reservoir heterogeneity is the synthetic effect of multi-factor, such as lithology, lithofacies and structure,etc. But heterogeneity is traditionally evaluated by some single factors. This single-factor method isdifficult to consider the effect of other factors. So in this paper, A new composite parameter called thecomposite index of reservoir heterogeneity (IRH) is raised. This index can reflect the reservoirheterogeneity, and is calculated by fuzzy composite evaluation. In the reservoir of fluvial factes in themiddle of No. 7 district in the Gudong oilfield, the six parameters, such as net-to-gross ratio, porosity,permeability, sedimentary microfacies, the top surface microstructure of reservoir, median of grain size, isuSed to calculate the composite index. The result coincides with practical production, and suppliedreliable geological data for project adjustment. Reservoir heterogeneity is the synthetic effect of multi-factor, such as lithology, lithofacies and structure, etc. But heterogeneity is tramonst evaluated by some single factors. This single-factor method isdifficult to consider the effect of other factors. So in this paper, A new composite parameter called the composite post index of reservoir heterogeneity (IRH) is raised. This index can reflect the reservoir heterogeneity, and is calculated by fuzzy composite evaluation. In the reservoir of fluvial factes in themiddle of No. 7 district in the Gudong oilfield, the six parameters, such as net-to-gross ratio, porosity, permeability, sedimentary microfacies, the top surface microstructure of reservoir, median of grain size, isuSed to calculate the composite index. The result coincides with practical production, andreliablereliable geological data for project adjustment.