In this paper,the impact analysis of air gap concerning the parameters of mooring system for the semi-submersible platform is conducted.It is challenging to simulate the wave,current and wind loads of a platform based on a model test simultaneously.Furthermore,the dynamic equivalence between the truncated and full-depth mooring system is still a tuff work.However,the wind and current loads can be tested accurately in wind tunnel model.Furthermore,the wave can be simulated accurately in wave tank test.The full-scale mooring system and the all environment loads can be simulated accurately by using the numerical model based on the model tests simultaneously.In this paper,the air gap response of a floating platform is calculated based on the results of tunnel test and wave tank.Meanwhile,full-scale mooring system,the wind,wave and current load can be considered simultaneously.In addition,a numerical model of the platform is tuned and validated by ANSYS AQWA according to the model test results.With the support of the tuned numerical model,seventeen simulation cases about the presented platform are considered to study the wave,wind,and current loads simultaneously.Then,the impact analysis studies of air gap motion regarding the length,elasticity,and type of the mooring line are performed in the time domain under the beam wave,head wave,and oblique wave conditions. In this paper, the impact analysis of air gap concerning the parameters of mooring system for the semi-submersible platform is conducted. It is challenging to simulate the wave, current and wind loads of a platform based on a model test. dynamic equivalence between the truncated and full-depth mooring system is still a tuff work.However, the wind and current loads can be tested accurately in wind tunnel model. Morerther, the wave can be simulated accurately in wave tank test. The full-scale mooring system and the all environment loads can be accurately accurately by using the numerical model based on the model tests earlier. In this paper, the air gap response of a floating platform is calculated based on the results of tunnel test and wave tank. full-scale mooring system, the wind, wave and current load can be considered simultaneously. In addition, a numerical model of the platform is tuned and validated by ANSYS AQWA according to the model test resu lts.With the support of the tuned numerical model, seventeen simulation cases about the presented platform, are studied to the wave, wind, and current loads. Then, the impact analysis studies of air gap motion regarding the length, elasticity, and type of the mooring line are performed in the time domain under the beam wave, head wave, and oblique wave conditions.