Maritime Guinea is subject to the development of numerous mineral ports enabling the benefits of the mining sector to be fully realized. However, in Guinea, as in most areas with fragile coastal ecosystems, port development has effects on the biophysical and human environment. In this case, it is necessary to put in place effective strategies to assess the mineral port development plan scenarios upstream of the projects. The objective of this study is to assess the scenarios for the development of mineral ports in Maritime Guinea in order to make better decisions. To do this, we have linked multi-criteria decision support (AMCD) approaches in a multi-stakeholder context with Geographic Information Systems (GIS). The process involved a diversity of actors involved in port development issues in Guinea. Eight scenarios and nine criteria for benchmarking scenarios were developed. The scenarios are divided into two groups, the first is linked to the individualistic strategy in the implementation of the ports and the second is part of the strategy of sharing of the ports. The aggregation of scenario performance during the AMCD process was performed using the Visual PROMETHEE software. On the one hand, the GIS enabled the development of environmental stress maps and port development plan scenarios, and on the other, the evaluation of certain criteria. The analysis results show the strengths and weaknesses of each scenario as well as their storage for each of the actors and for the group. The scenarios oriented towards a strategy of sharing infrastructures generate more interest for all the actors. They have the advantage of meeting port infrastructure needs with shared costs. They both create wealth for the national economy and reduce environmental and social impacts.