The analysis of the modern informative systems is conducted. Classification of structural elements of the informative system is resulted on functional signs and the generalized structure functional chart of the informative system is built. It is indicated on influence of row of external and internal factors of affecting efficiency of functioning, both separate elements and informative system on the whole. On the basis of the conducted analysis of structure functional construction of the informative system the hierarchical complex index of efficiency of its functioning is developed.
informative system, man-machine system, parameters of subsystems, index of quality, index of efficiency, tensor description and calculation