Abstarct: Any change of water velocity in the pipeline systems induces a change in pressure. This phenomenon is one of the important cases of transient flows, known as water hammer, and has been observed for many years by researchers. This creates considerable dynamic forces to pipeline’s structure. If these forces can cause movement of the pipe network phenomenon called fluid structure interaction will occur. This phenomenon involves transmission of energy and momentum between the pipeline's structure and the fluid and is normally produced by intensive change of flow rate and fluid pressure or mechanical factors in pipeline systems. Transient flow models are required for design, analysis and safe operation of the pipeline systems. Several numerical approaches have been proposed for modeling of transient flows, such as: Method of characteristics (MOC), finite volume (FV), finite difference (FD). Among these methods, MOC is the mostly used method for its simplicity and superior performance over other methods. Using MOC faces some serious shortcomings. For example, application of this method requires that only one device is located between any two pipes. Otherwise, a new boundary condition has to be derived for each combination of the devices that may be used in the pipeline system. An Implicit Method of Characteristics (IMOC) is proposed in this section as a remedy for the above-mentioned shortcomings of the conventional MOC. For this, an element-wise definition is used for all of the devices that may be used in a pipeline system and the corresponding equations are derived in an element-wise manner. These equations are derived independent of the location of the devices and flow direction. So Implicit method of characteristic is proposed in this study as agood method for simulation of fluid–structure interaction. In the end, for evaluating method results we solved one of the famous laboratories reference problems with Implicit method of characteristic and then compared with previous results of MOC. Obtained results showed that implicit method of characteristiccan be an appropriate method for solving hyperbolic system of differential equations.