The invention provides a passive wave absorbing and roll damping power generation device of a floating draught fan platform. The passive wave absorbing and roll damping power generation device comprises the floating draught fan platform, wave absorbing floaters, buffer springs and linear generators. The floating draught fan platform comprises platform pile legs and brace rods. Each linear generator comprises a stator and a rotor. The passive wave absorbing and roll damping power generation device can reduce motion response of floating draught fans under the wave action and can also absorb wave energy and convert wave energy into electric energy. The buffer springs and the linear generators can play a role of roll damping, increase motion damping of the floating draught fan platform and can reduce motion response of the floating draught fan platform under the wave action. The wave absorbing floaters absorb wave energy and convert wave energy into motion mechanical energy of the wave absorbing floaters. The motion mechanical energy of the wave absorbing floaters can be converted into electric energy through the linear generators. The passive wave absorbing and roll damping power generation device can effectively reduce the motion response of the floating draught fan platform under waves, enable the draught fans to be in a more stable operating state and improve the working efficiency and safety of the draught fans.