The invention relates to a cheap, simple, environmentally-friendly and high-efficiency solar thermal power machine and a power generation system, which solve a series of technical problems of low thermal energy conversion efficiency, high thermal energy consumption of a system, complexity of a heliostat control system, bulky equipment scale and high equipment construction cost of the conventional solar thermal power and generation machines. A rotary type triple-stroke solar thermal power machine and a power generation system consist of a solar heat-collecting and heat-conducting oil closed circulation loop, a totally-closed solar thermal power machine system and a totally-closed low-boiling point working medium circulation loop. A heat machine system continuously works by adopting three stroke modes of direct working medium injection in a cylinder, vaporization explosion expansion work and exhaust steam condensation; and the exhaust steam working medium can be recycled by returning to a condensation system to be condensed into a liquid state. Power output is generated through the heat work conversion and drives a generator to generate electricity. The clean, inexhaustible and freely-available solar energy can be used, so that scattered, small-scale and large-range solar thermal energy utilization can be fulfilled.