In recent years, due to the reduction of oil resources, both on lands and in shallow waters, exploration and extraction of oil resources are played in deeper waters. Therefore, the need for appropriate structures suitable for deep waters is obvious. The semi-submersible platform is a specific type of such platforms which is used in deep waters. These platforms are utilized for different purposes such as drilling, exploration, extraction, loading and off-loading of petroleum products under the influence of external forces caused by wind, waves, current, etc. True understanding of the dynamical behavior of the semi-submersible platform in damaged condition can help designers to reduce the environmental hazards. Platform structural damage can be accompanied with the entry of water in the reservoirs of platforms which will lead to the change in platform stability and excessive increase in the platform movements. In this research, the AMIRKABIR semi-submersible platform is modeled in the Marine Engineering laboratory of the “Sharif University of Technology”. The model scale was 1:143 and the environmental conditions of the Caspian Sea were considered the amount of water entering one of the pontoon reservoirs was set to follow that similarity scales. The model was installed in the flume tank using a spread mooring system. For the environmental conditions of the Caspian Sea, the platform was tested under both head and beam sea directions. The results of the conducted tests are represented by platform motion Response Amplitude Operators (RAOs).