Abstract: Based on an actual engineering project involving a floating scale prototype， this article employs a timedomain analysis method to numerically simulate the transient response of a semi-submersible floating wind turbine platform. It extensively investigates the influence of varying anchor chain length and counterweight mass on the pre-tension of the mooring system and the motion response of the floating platform. The results indicate that the amplitude of pitch， heave， and surge responses of the floating platform initially increases and then decreases with an increase in mooring length. Increasing the mass of the counterweight leads to an initial increase and subsequent decrease in pitch and heave responses， while the surge response initially decreases and then increases. When simultaneously changing both the mooring length and counterweight mass， the counterweight mass does not affect the variation pattern of platform motion response caused by mooring length.

Key words: floating wind turbine platform, mooring system, length of anchor chain, counterweight, motion response