:The main objective of subsea cutting and drilling is removal or displacement of structures that are disabled and have sunk under the sea. The choice of method is influenced by the specific structure configuration (shape, water depth, weight) and available equipment. Electrochemical drilling processes are a relatively recent development arising from the need to drill very hard materials at economic rates. Metals of any hardness is removed by anodic dissolution in an electrolyte, in a process which may be regarded as reverse electroplating and Electrolysis laws are the base of this process. Electrochemical drilling (ECD) is a nonconventional machining method which can be used for subsea operations in which seawater is used as electrolyte. Subsea electrochemical drilling may be used for making a large diameter hole in one step without tool wear. In this study, a designed mechanism is presented to make a hole with a diameter of 30 centimeters and a thickness of 5 cm under the sea. Tool feed system, clamping type, gap size control system, slug holder and how to inject electrolyte to the region of the machining process are what have been considered in the design. Several kinds of gap size control system was studied and current based control system was chosen. This control system monitors electrical current magnitude and modifies feed rate position by sending signal to hydraulic circuit. This design was modified for drilling a curved hole on the subsea structures. Finite element method (FEM) was used for electrochemical drilling simulation and its formulas was extracted based on Laplace equation. Comsol multiphysics software was applied for process simulation. Effects of tool thickness, edge radius and tool feed rate were investigated. The machining parameters were proposed in order to increase of material removal rate and for the assurance of process feasibility under the sea. Keywords: Subsea drilling, electrochemical drilling, finite element method, Comsol, curved hole