The small layers 54-68 in the upper section of Guantao Formation in No.6 Block of Gudong Oilfield are braided river deposits that have complex architecture. At present，this oilfield has faced several problems including extra-high water cut，high distribution of remaining oil，difficulties in stable production. Therefore，the key to solving those problems is to carry out fine anatomy of the reservoir architecture. The fine architecture characterization of the inner part of the sandy braid bar is taken as the entry point. The internal architecture of the sandy braid bar in the upper section of Guantao Formation in No.6 Block of Gudong Oilfield was analyzed. Combined with the characteristics of sedimentary microfacies of the sandy braided river of Gudong Oilfield，the different hierarchical levels of architecture interfaces in the sandy braided-river reservoirs were identified. Based on the well correction in dense pattern，the quantitative characterization of the scale of the reproduction body in the braid bar of the braided-river reservoir was realized. The range of parameters for four-grade architecture was determined. Among them，width is 100-350 m，length is 400-500 m，thickness is 4-12 m of the braid bar.The length of the braid bar has positive correlation with the width of the braid bar，and the width of the braid has almost positive correlation with the thickness of the braid bar. The range of parameters for three-grade architecture of the off-silt and accretion body was determined. The average dip of the off-silt at the head of bar is 0.93° and that at the end is 0.53° and that at two wings is 1.47°，and the length of single accretion body in the braid bar at direction of long axis is from 280 to 800 meters，and its width is from 165 to 400 meters. The width of the the off-silt may be from 250 to 700 meters and its length may be from 150 to 350 meters.