Abstract: Numerical analysis of fluid-structure coupling vibration of fluid-conveying pipe was carried out by method of characteristics (MOC). 14-function model is adopted in the numerical analysis, and the MOC is improved to get higher numerical analysis precision. Confirming conditions of time step, Dt and divided number of straight pipe, N are presented, self-adaptive-mesh-manifolding method of modifying mesh spacing Dz close to boundary is put forward to catch accurate change of fluid pressure. A numerical simulation research on coupled vibration response of a hydraulic system is carried out, the result shows that numerical result is consistent with experiment result, and the numerical method introduced is validated.