In this project, a boundary element method was used to extract added mass coefficients of an Autonomous Underwater Vehicle (AUV). Dynamic Motion of underwater vehicle was analyzed by precise mathematical models known as dynamic models. Dynamic models include all forces and moments on the vehicle which are expressed by dynamic and hydrodynamic coefficients. Added mass coefficients are an important part of hydrodynamic coefficients. The role of added mass coefficients is estimating the forces on the body when accelerated. Added mass actually refers to a hypothetical volume of fluid particles accelerated with the body. The added mass appears during the body acceleration inside a fluid, and during changes in the depth and direction of the motion. Accurate prediction of added mass coefficients can lead to a more precise dynamic modeling of an underwater vehicle during its maneuvers. There are a number of experimental, analytical and semi-experimental and numerical methods which can be used to calculate added mass coefficients of submersible vehicles. The experimental method includes accelerating the body in a towing tank and measuring the force associated with the acceleration. The numerical method includes using computational fluid dynamics and boundary element method. In this project, by assuming potential flow around the vehicle and simplifying the equations to Laplace equation, to resolve it, boundary elements method was used and at the end, the added mass of the float was calculated. The advantages of this method are solving the infinite boundary, storing information without requiring much space, calculating the derivatives of the functions and analyzing complex geometries, high-speed computing, etc. Using triangular elements was the advantage of the present project as compared to other projects in this area. Triangular elements increased the accuracy in the production and analysis of complex geometry. By sphere and Ellipsoidal geometries, we tried to solve the two sample problems. After comparison and validation of the results of numerical method with those of the analytical solution, we analyzed the original geometry (AUV) designed by the Zirdarya science and technology institute of Isfahan University of Technology, and compared these results with those of other methods. Among the key findings of this project, we can refer to its very good accuracy in the analysis of geometry of spherical and elliptical in comparison with analytical solution and also the ability of boundary element method in analyzing complex geometries such as AUV or submarine. Keywords: boundary element, autonomous underwater vehicle, numerical solution, hydrodynamic analysis, added mass, AUV