Cuban national upgrade on its economic development model has identified science, technology and innovation (STI) as a strategic tool for the sustainable development of the country. Recently approved State and Government documents, even the Constitution, as well as new public policies and its correspondent framework regarding National STI System (STIS)-which include Science and Technology Parks, High Tech Enterprises, STI Programms and Projects, etc.- have confirmed the importance of STI. On this paper, we proposed a characterization of Cuban STI System, based on the analysis of national STI indicators. We also take into account some of the main processes and actors of the STIS, as well as their interactions, to identify five main achievements and five critical challenges for future STI policies, related to governance, institutionality, funding, human potential, interfase activities, infraestructure, as well as STIS evaluation. We considere this elements could be critical to achieve the transformation of the National STI System, as a main contribution to the upgrade of the nacional economic development model.