Abstract: In engineering practice，some hydraulic problems such as normal depth，critical depth and water surface profile，which are higher implicit functions.There is no analytical solution，and it is difficult to solve directly.Traditional method is to use chart checking，iteration or trial algorithm to solve the problem，but the calculation is complicated and the precision is not good.The problem of high order implicit function equation in hydraulic calculation can be solved quickly and accurately by using VB programming language.When initial value of iteration，roughness，flow rate，bottom width，bottom slope and slope coefficient are known，shortcut key can be used to realize multiple iteration calculation，and normal water depth value with high precision can be calculated.Application of VB iterative function in solving high order implicit functions were introduced，and application of programming language in simplified calculation and high precision solution were explored.