Electrochemical machining (ECM) is a modern machining process that removal of workpiece atoms in it relies on the principle of ion movement in the electrolysis cells. Compared with traditional machining methods, ECM takes many advantages such as; hard and brittle material machining ability with complicated shape and fast material removal rate without any residual stress whereas it's a non mechanical process. Because of it's advantages against traditional machining, it used for manufacturing of many complicated and strategic pieces that makes from hard and brittle alloys such as; Nickel, Titanium or Molybdenum alloys that needs minimum structural defects.The most important problem in ECM is to obtain required shape of workpiece by using designed tool. In the present work, firstly the fundamental of ECM processes is perfectly studied. Then a technique is developed for simulation of ECM processes in the present of Electric, Magnetic, Thermal and Fluidic fields based on equations govern on them by Finite Element Method (FEM). This technique is capable of handling three-dimensional free surface tool design. It possesses high computing efficiency, good accuracy and flexible boundary treatment without the need for iterative procedure. At continue, a simple model of ECM set has manufactured and the process operations has tasted on it. This set is first ECM in its kind that all substructure's produced by own technology. Result of experiments shows that how electrical, magnetic, thermal and fluidic fields effect on potential field distribution. Therefore we can use ECM simulation to guide ions in proper direction to converge electrode surfaces without any experiment cost. The implementation results are compared with simulation results to verify viability of proposed method. At continue, two examples of tool design for turbine blade are given to demonstrate this method. In the end, there is a summary of thesis and suggestions for further studies. Keywords: Electrochemical Machining (ECM), FEM, tool design, non iterative algorithm, free surface forming.