The invention discloses a digestion and determination method of heavy metals in a waste dust-collecting bag, and relates to microwave digestion of the waste bags generated by iron and steel smelting and non-ferrous metal smelting (such as lead-zinc smelting and copper smelting). The method comprises the following steps: mixing the waste dust-collecting bag with a digestion acid system composed ofnitric acid, hydrogen peroxide and hydrofluoric acid in a polytetrafluoroethylene-sealed pressurized digestion tank at normal temperature, shaking up and keeping standing overnight; and performing the microwave digestion under certain conditions and then performing heavy metal determination. By adopting the method, the waste dust-collecting bag is made into a digestion solution, and flame atomic absorption spectroscopy (FAAS) is further adopted for determining the content of the heavy metals in the digestion solution.