Taking DeepCWind type semi-submersible floating platform as the research object and using ANSYS/AQWA software, the effects of the tension, stiffness, mooring forces and horizontal length of mooring lines on the moving performance of this platform were investigated in consideration of different directions of environmental loadings, the length of mooring lines, and whether the mooring lines break or not. The results show that: mooring stiffness and mooring force suppress the floating platform’s motion together; surge and pitch motions reach the minimum value when the incident angle is 90o; the surge is proportional to the cable length, while the pitch is inversely proportional to the cable length ; on the side of the receiving wave, the broken cable will significantly increase the tension of the adjacent sides and increase the surging motion, but it has little influence on the pitching motion.