The accommodation platform is usually connected with a drilling or production platform by a telescopic gangway that provides accessibility of walk-to-work for stuffs. The safety of gangway is crucial during offshore operations. This paper presents a cooperative guidance law for two DP semi-submersible platforms based on model predictive control so that the stroke of the gangway is within its safety range. The prediction model considers both the global positioning of the platforms and the relative positioning between them, which can effectively reduce the relative movement. A self-developed simulation program is used to investigate the gangway responses when the platforms are exposed to environmental loads in different directions. The simulation results demonstrate the efficacy of the proposed cooperative control strategy in reducing the gangway extension and rotation。