Wave energy converters (WECs) based on the hydraulic Power Take-Off (PTO) mechanism are proposed in conjunction with a modularized floating platform for the wave energy harvesting and pitch motion suppression of the platform. A rigid multi-body dynamic model is developed where the WEC is considered as a linear damper to absorb the kinetic energy of the platform induced by waves. Numerical analysis is firstly carried out for a four-modular semi-submersible floating platform. The effect of the PTOs on the pitch responses of the hinged floating platform is studied in irregular waves, and an optimal balance between the energy extraction and pitch suppression is achievable. Taking capture width of energy extraction as an objective function, the damping coefficient of the PTOs is optimally determined by combining an external penalty function method and the Hooke Jeeves method. Further the effect of the number of floating modules on the energy absorption and responses of the floating system is evaluated.