The aim of the research is to analyze the methodological aspects of the decision support systems (DSS) processing and the DSS substantial classification. The novelty of the results lies in the fact that classification features and their possible values, being the subject and the goal of such a system, are suitable to the designed managerial decisions, as well as the classification can be used to create a specific DSS. Hypothesis: it is possible to allocate classification features of DSS, the list and the contents of which will determine the substantial (enlarged) DSS classification suitable to the construction of concrete DSS. Also, the selected classification features and their values can be used to construct DSS content, i. e. to design a block structure of created DSS. Method of research: systematic and logical analysis on the base of the subordination of the created DSS to aims and content of the generated managerial solutions. Results: based on the reasonable classification features and their values the substantial classification of decision support systems is built, as well as the block structure of the DSS, considered in the wide, and in the narrow sense as well. The research is supported by the grant RFBR 13.15.202.2016. The results published in the paper were presented at the International Scientific Conference «New Challenges of Economic and Business Development - 2016. Society, Innovations and Collaborative Economy», Riga, http://www.evf.lu.lv/conf2016.