As hydraulic power has big dynamic fluid force and fast response, fluid power system is used in a wide variety of applications from precision control systems to heavy industrial systems. There are many hydraulic components in hydraulic power systems. Among them, accumulator has several functions such as pressure regulating and storing pressured fluids and it also can relieve the power of hydraulic pump. So, in many hydraulic systems, accumulators are used in proper positions. This thesis develops hydraulic systems which contain exciting damper, accumulator and some other hydraulic components. An external excitation is given to the hydraulic damper to simulate the system pressures and flow-rates. From these simulation data, required hydraulic power can be calculated and a proper size of the accumulator can be designed. The hydraulic system with the designed accumulator is restructured to calculate the overall required system power. Finally, analysing the difference between the hydraulic systems without an accumulator and the hydraulic systems with the suggested accumulator, it is investigated that how effective the accumulator is to save the system power.