This experiment is one of the improved types of Orbal oxidation ditch technologies belonging to the sewage treatment engineering project to be carried out at the small town in western China supported by the Holland Grant Project.The survey for similar Orbal oxidation ditch was performed on-the-spot for safety of engineering design.The experiment individually focused on the velocity distribution of concentration ellipse shape represented in oxidation ditches existed in sewage treatment plants,and confirmed the rationality of aeration and the submersed flow driver power designed.The result shows: Firstly,for such oxidation ditch,it is easy to cause sediment resulted from complex waterpower of crook,and affect blend condition.Secondly,the sediment is prevalent,especially in some places.Finally,the design power of aeration and submersed flow driver are insufficient.