Abstract：Based on the experience of rock mechanics study accumulated in the past 50 years in the fields of hydraulic and hydropower engineerings，some essential considerations including the purposes and the distinctive characteristics of these studies are studied. It is emphasized that the three parts of rock mechanics study in hydraulic engineerings，i.e.，reconnaissance of rock mass，utilization of rock mass and reinforcement of rock mass，are closely related to each other. In addition，some attitudes associated with rock mechanics study in hydraulic engineering in aspects of uncertainties of rock mass and the corresponding strategies，phasic problems in rock mechanics study，the main contents of rock mechanics study，characteristics related to the three kinds of rock engineerings(dam，rock slope，and underground openings)，relationship with engineering geology and engineering design actual behavior monitoring of engineering rock mass，and general comments considering the environmental protection and the maintenance of ecological equilibrium are presented and summarized.
