Abstract: A submersible power generating system for generating electricity from total potential energy of still water has a closed endless rotation cascade cage apparatus, a compressed air generating apparatus, a compressed air storage apparatus, a gas injection apparatus, a gas retrieving apparatus, a building, an initiation power supply apparatus, a power generating apparatus, an intelligent control apparatus, a safety apparatus, a water treatment apparatus and a maintenance facility. The submersible power generating system makes full use of natural properties of water and air, performs continuous energy conversion, and achieves energy balance in three stages, so as to directly converse total potential energy of still water into electric energy, thereby achieving stable power production and obtaining inexhaustible and clean electric energy.