In this paper we will study dynamical modeling of a parallel robot Hexa using Lagrangian equation of the first type. Because of complexity and nonlinearity of parallel robots' relationships few works are done on their dynamical modeling. Although Newtonian approach is a straightforward method, it may not directly result in a suitable model for most of famous control schemes such as robust, adaptive or robust-adaptive while Lagrangian formulation does so. Since parallel manipulators are usually very nonlinear, using Lagrange equation of the second type is a tremendous work while Lagrange equation of the first type decreases much complexity. Also we have written software, HEXA STUDIO, suitable for design, kinematics, dynamics and control of the Hexa robot.