Abstract: Relationship of longitudinal transport and vertical distribution of sediment in a river is the one of mutual interdependence. Vertical distribution law of concentration in non-equilibrium transport is a core subject of the theory and its in-depth study is of great significance to advancement in river sediment discipline. Recent theoretical studies on this subject are lacking, while a great number of correspinding results for equilibrium tranpsort including relatively mature theories were previously reported. This paper focuses on an analysis of Hanqiwei's theory about the sybject, and suggests that further discussion is needed on his assumption that the parameter of vertical average concentration distribution in equilibrium transport is applicable to derivation of the formula for non-equilibrium cases. We also suggest that it would be impossible to achieve a breakthrough in the vertical distribution law of sediment concentration in non-equilibrium transport until a great numbe of detailed flume tests are completed. And a demonstration of such tests is included.