The numerical simulation on 7 kinds of section of the canal was made by the method of hydraulic caculation for water in the channel.Comparing the advantages of various canals in the same flow,the advantages of less cover of soil surface area of U shape canal is obtained.Within numerical simulation,the results show that flow and water depth of various canals were correlated.The fitting function equations of flow and water depth was calculated by "SPSSS" statistical analysis software.The depth of trapezoidal channel with U-shaped cross section channel flow water level is a function of linear correlation,the other section of the canal is quadratic function curve.