The invention discloses a solar thermal power generation system by thermoelectric conversion, comprising a sunlight-concentrating and receiving module, a solar tracking module, a photothermal-conversion module for absorbing sunlight then transforming sunlight into thermal energy and a combination of semiconductor thermoelectric module, the combination-type cooling module is under the semiconductor thermoelectric module. In the invention, TE module can directly convert solar thermal and waste heat to electricity without heat transfer medium, heat storage tank, turbine, and mechanical moving part, thus realizing small scale, compact system with high efficiency; Due to the adopting of low concentrating lens with tracking system and compound waste heat supplying module, thus reducing floor area and effectively improving temperature difference and power generating efficiency of the overall system. In comparison with that of traditional solar thermal power generation system, the new system kept the advantages, including: low investment and low maintenance cost. In comparison with that of solar cell power generation system, the system has the advantages: large power in small area and possible in stable output; furthermore a heating source apart from solar energy is introduced to guarantee the stable current supply.