This paper proposes new control method of maximum power point tracking for the tidal energy generation system using the duty ratio control of buck type DC-DC converter. An advantage of new MPPT(Maximum Power Point Tracking) control method presented in this paper is not necessary to use the tidal turbine characteristic at various tidal speed and measure the tidal speed or/and the rotation speed of tidal turbine for generation. Therefore the resulting system has the characteristics of lower cost, higher efficiency and lower complexity. Proposed control method was analyzed mathematically and tested by computer simulation using Matlab Simulink . And the fuzzy controller was applied for regulation of duty ratio.