Abstract: Numerical method for computer solution are used for fluid flow in long distance pipeline, such as characteristics method, implicit difference method and so on. The characteristics method solution is applied extensively but the implicit difference method is little used for fluid transient problems. This piper.devoted to unsteady fluid flow.analyzes the advantages and disadvantages of characteristic method and implicit difference method, the calculation results obtained makes clear that the implicit difference method is suitable for analysis of fluid transient and less discrepancy.