Abstract: Study of reservoir heterogeneity plays an important role in the exploration and development stages of oilfield,especially in the later stage of development.With the method of fuzzy mathematics to calculate heterogeneous synthetic index and permeability heterogeneity parameter,we conducted a quantitative study to investigate the second member of the Shahejie Formation. Tuo 28 fault block of Shengtuo Oilfield. The results suggested that the heterogeneities of interlayer,internal and plane are strong in the reservior beds.However as the development of further waterflood ,the heterogeneity shows a trend of reducing but the range of reduction is small and the heterogeneous degree of each substratum and rhythmic unit is apparently different in various stages of development, Sedimentary microfacies controls the heterogeneous degree, diagenesis makes heterogeneity complicated and the deficient injection and production pattern increases the heterogeneity in evidence.The results of study have good effects in increasing production of well bed ,well pattern adjustment,new well drilling and bring great economic benefits.