The invention discloses a preparation method and applications of a loaded-type bismuth tungstate photocatalyst. The preparation method comprises following steps: bismuth nitrate pentahydrate and sodium tungstate dihydrate are dissolved in water, an obtained mixed solution is introduced into a reaction kettle, heating reaction is carried out, and then centrifugation, washing, drying, and grinding are carried out; Fe(NO3)3.9H2O is added to a grinded product, an obtained mixture is stirred at a certain temperature and then is subjected to calcining so as to obtain the Fe2O3/Bi2WO6 composite photocatalyst. According to the preparation method, Fe2O3 and a photocatalytic material are combined, the obtained composite photocatalyst possesses a heterostructure, Fe2O3 is narrow in forbidden bandwidth, utilization of visible light is realized; combination with Bi2WO6 is capable of improving the light adsorption capacity, increase photocatalytic quantum efficiency, and increase solar energy utilization rate. The composite photocatalyst is excellent in reutilization performance, high in degradation efficiency, low in cost, safe and environmental-friendly in production; no harmful pollutant is discharged; and the potential application value in the fields of degradation of microcystins, environmental purification and new energy development is achieved.