The cylindrical FDPSO, applied in the South China Sea, was taken as an example to study the change rule of FDPSO’s heave and pitch amplitude under different damping plate cone angles. The wave loads on FDPSO were calculated by three-dimensional potential flow theory, and the viscous damping was acquired through different methods, then the response transfer function of FDPSO was calculated. The spectrum analysis method was used to forecast the heave and pitch response, and the pitch response caused by second order wave loads was calculated. The results show that the heave movement of cylindrical FDPSO is intense, but the anti-shake performance is good. The increase of damping plate cone angle is not conducive to the control of FDPSO’s heave and pitch motion response, and the second order wave loads have a huge influence on cylindrical FDPSO’s pitch motion response, which should be paid attention to.