Abstract: Fuyu oilfield has the characteristics of big reservoir permeability differential,stronger intraformational heterogeneity and different level of drilling fluid pollution,which seriously restricted the oil and gas reservoir identification.Through laboratory evaluation experiments on the drilling fluid damage to reservoirs,the mathematical model of different permeability reservoir drilling fluid pollution with the change of time has been established and the heterogeneity of reservoir drilling fluid pollution law has been analyzed.Combined with block reservoir sensitivity data at the same time,by comparing the method of gas logging permeability cores before and after pollution,the drilling fluid pollution mechanism of heterogeneous reservoir has been studied.