A multi-body offshore platforms with weak nonlinear link chain was taken into consideration in this research. Thinking floating piers as mutual coupling units of network structure

boundary element method (BEM) can be used to obtain wave parameters

then floating platform‘s time domain response in different wave angles can be calculated by Runge-Kutta iteration method. The result of numerical calculation shows that the amplitude response area in beam waves is obviously greater than that in following waves

indicating that it is more difficult to find the frequency of non-response region in a situation of beam wave. In analysis of time domain responses

the max amplitude is sway in beam wave

and since sway in beam wave is significantly affected by bending resonance of internal system

jump of amplitude can be easily observed in specific wave angles.