The present research deals with the numerical prediction of the air gap within the 6th generation of deep-water drilling floating semi-submersible platform and the experimental studies on the slamming loadings onto the structure. The survivability of the floating model with a mooring system was tested under extreme wave of 10-year return period. In the numerical simulation of the Gaussian method,the narrow band model was applied to obtain the first-order wave surface equation and the modified second-order wave surface equation. The hydrodynamic re-sponses of the floating body,i.e. radiation damping,added mass,second-order wave excitation force and drifting force,were computed by using the potential flow theory based on higher order boundary element method in fre-quent domain. In the experimental analysis,high-frequency sensors were installed at the lower deck to measure the wave slamming loads. Equivalent truncated mooring system was applied to make sure position of the floating body in the wave tank. The comparison between the numerical and experimental results showed the numerical model un-derestimated the air gap of the floating body. Nevertheless,the predictions of the high risk spots underneath the floating deck that is prone to wave slamming obtained from both models were agreeable to each other. The experi-mental results also revealed that the wave slamming events often occurred at the connection point between the rear columns and the lower deck.