Abstract: Based on two model tests of flow in curved channel and referred to some studies for the country and for abroad summarized and analyzed the flow around river bend. Firstly this paper describes the evitable tendency for the meandering flow of natural river and the characteristics of spiral flow in river bend forming by circular secondary flow with principal flow. The change of direction and position of principal flow, the intensity of circular flow,the transverse slope of water surface across river bend etc.were analyzed and the calculation fomulas were derived. Secondly the calculation method for sectional velocity distribution and unit discharge distribution along river width are given and calculation formula of scouring depth in river bend is obtained analytically. So we can calculate the equilibrium cross section for scouring and silting in river bend by these formulas.