Abstarct: The decreasing and increasing velocity of flowing fluid in the closed path, causes the waterhammer phenomena. Pipe deformation caused by forces deriving from water hammer leads to fluid-structure interaction (FSI) phenomenon. Various numerical methods has been applied to solve the FSI equations including finite difference methods, finite volume, finite elements or combination of these methods. Characteristics method and Goduno method are count as successful methods in this field. In characteristics method, time and space steps should be proportional to each other. Therefore, time steps should be determined according to the dimensions of the case. Hence, to determine the time steps in characteristics method interpolation should be carried out. Due to using the Reyman problem, Goduno method, is a time consuming of solving method. In this study, meshless method, which is count as an effective method for solving equations, has been applied. Pressure distribution plot, velocity distribution, wave diffusion velocity plot at pipe and consequent stress at pipe in the beginning and end of the system including reservoir, pipe and valve have been investigated. Its results verified by results of the characteristics method. Results has shown that the meshless results are in good fit with the results of characteristics method.