Hong Kong-Zhu hai-Macao Bridge, connecting world famous tri-cities in China, will consists of three different construction elements: a man made peninsula, a world’s longest and widest immersed tunnel and a cross-sea bridge. The key point of this megastructure is the construction of the immersed tube tunnel construction. The accuracy of tunnel element positioning directly determines the quality of tunnel construction. In order to study the behavior of elements during its lowering to the sea bed, the scaled model test has carried out in the Key Laboratory of High-speed Ship Engineering of Ministry of Education, Wuhan, China. Experiment was carried out to investigate the motion responses of the tunnel element in the immersion under wave and current actions and the tensions acting on the controlling cables of its immersing system. A concise description of the model wave-current test is carried out, and the variation of motion responses of the tunnel element and cable tensions against wave, current and immersing depth were obtained, which could be a guidance to the construction of the immersed tunnel of Hong Kong-Zhu hai-Macao Bridge.