The basic principle and method of 3D stochastic modeling of sedimentary microfacies are discussed according to geological and acoustic impedance data of welllogging constrained seism inversion,and a case study according to stochastic modeling of fluvial facies reservoir of the Minghuazhen Formation of Neocene in a certain block of Bohai Bay Basin is used to show the general process of this research. The general process of this study includes sedimentary microfacies interpreting within boreholes,welllogging constrained seismic inversion,probability relation analysis between acoustic impedance and sedimentary microfacies,selecting the method of stochastic modeling,analysis of geological statistical characteristics,3D stochastic modeling and assessment to multisolutions of forecasting of stochastic modeling.The results show that there are some correlative probability relations between acoustic impedance and sedimentary microfacies,and the stochastic modeling of sedimentary microfacies can make an effective assessment to multisolutions of reservoir forecasting by synthetically applying multidisciplinary information,including seismic data.