The invention discloses a thermal energy purifying method comprising the following steps of firstly, placing ore sand into a hydrochloric acid tank; secondly, preparing a device for linking a boiler and the hydrochloric acid tank; and thirdly, heating the hydrochloric acid tank, and exhausting acid mist formed by the hydrochloric acid tank by using a vacuum exhausting pump. According to the thermal energy purifying method, a method for eliminating impurities in quartz sand through heating hydrochloric acid is adopted, so that the defect that the impurities can be effectively removed in an electromagnetic rod way in the prior art is made up, and resources are favorably utilized.