We can get quantitative data of the planar distribution in sedimentary system of braided river,so as to establish the relationship about the sedimentary system.This paper introduces the research status of modern braided river sedimentary,compares the two types of sedimentary characteristics about braided river.This paper introduces a method to study the scale of modern braided river,and then measuring the width and length of braided bar and the width of braided stream belt in different regions and sedimentary environment,so we get a lot of measuring datas.On this basis, we get two types of relational expressions,one relational expression is about relation of braided bar"s width and braided bar"s length,the others is about relation of braided bar"s width and braided stream belt" width.These relational expressions can provide reference for the size distribution of sandbody configuration,guiding quantitative research of reservoir configuration in braided river.