It is noted that currently the classification of hydraulic engineering constructions causing many arguments and misunderstanding of the classification process itself is the most topical issue. To understand the algorithm of classification of these constructions and implement it correctly it is required to know the history of classification of hydraulic engineering constructions stated in the present Article. Here is also the information provided from the earlier valid construction norms and regulations. Data on the criterion of hydraulic constructions classification is given starting from 1954 and to present time. Owing to comparison of such criterion, it is visually visible how the requirements to identification of the class of hydraulic engineering constructions were changing. The main postulates of classification of hydraulic engineering constructions are stated with the course of time what is interesting most of all for the owners of hydraulic engineering constructions and the operating organizations, expert centers when conducting expertise of industrial safety declaration of such constructions, and also for state supervision bodies.