The research presented in this paper brings out a moored twin-MCTs design and analysis of blade loads affected mooring system hydrodynamics. Firstly, a twin counter-rotating turbine system and a normal ocean current turbine system, using NACA63818 hydrofoil, are modelled and simulated in Orcaflex. Then to take blades loads into consideration, a twin counter-rotating turbine system, with specific-sized rotor, was modelled in Orcaflex. Different hydrofoils from NACA 63XXX foil family are used to build rotor model. Considering that Orcaflex uses Blade Element Method to calculate rotor performance which is not accurate enough and not timely adjustable, to better predict the performance of MCT in less computation cost and predict accurate mooring dynamics and displacement, a combination has been given between Orcaflex and in-house code M-BEMT, written in Matlab. Finally, the results of mooring line effective tension and turbine body motions are compared. The whole moored MCT system was evaluated in a dynamic environment to give suggestions to design proper mooring system.