Following the study of braided river reservoir architecture，the flow unit distribution controlled by reservoir architecture becomes more and more important. Taking the braided river reservoir in the Guantao Formation in Dagang A Oilfield for example，the thesis focuses on the method of classifying braided river flow units and their distribution law based on reservoir architecture analysis. Firstly，based on the seepage barrier identification，the connected volume division and seepage variation analysis，as well as considering the reservoir heterogeneity，four parameters including shale index，porosity，FZI（flow zone index）and K/μ were selected to divide the reservoirs into five types ofⅠ，Ⅱ，Ⅲ，ⅣandⅤby using the method of cluster analysis. Secondly，every single well was interpreted and the type of flow unit was identified according to the standard. And the distribution both in plane and on section was studied under the guidance of reservoir architecture and flow unit model using interactive analysis between horizontal and sectional characteristics of flow unit. The results can be concluded as follows：①Horizontally，the core part of channel bar and sand-filling river course are generally served as the well reservoir flow unit. ②Vertically，the flow units in the bottom are generally better reservoirs than those in the upper part，and the type of flow units above and below the interlayers inside of the channel bar does not always remain the same.