The invention discloses a direct-contact heat exchange tower type solar thermal generating station system and a working method thereof, and belongs to the field of solar thermal utilization. The system comprises a heliostat field, a heat absorber, a molten salt heat storage and release subsystem, a turbine, an electric generator, a preheater, a cooler and a compressor. Sunlight is reflected into the heat absorber through the heliostat field, after air is compressed, high-temperature and high-pressure air is generated through the heat absorber to push the turbine to apply work for power generation, and the working method is adjusted by combining with the molten salt heat storage and release subsystem according to differences of solar energy intensity. According to the direct-contact heat exchange tower type solar thermal generating station system and the working method thereof, by means of the characteristics that molten salt is low in vapor pressure and wide in using temperature range, an air and molten salt direct-contact heat exchange mode is adopted for replacing traditional wall-type heat exchange, the heat exchanger efficiency can be improved, and a heat exchange temperature difference can be reduced; meanwhile, the air serves as a working medium, the phenomena of large-range flow-induced corrosion and frozen blocking of the molten salt in a pipeline are avoided. Meanwhile, continuous and stable operation under different solar energy intensity conditions can be achieved, and stable high-quality electric energy can be provided.