In view of how to effectively study the blowhole defect of the fusion-cast charge, a method of presetting blowhole into the fusion-cast charge with an injector is proposed. Through theoretical analysis, simulation calculation, process test and application verification, the charge column with porosity defects can be prepared stably and reliably when the gas injection timing is accurately controlled, and the volume of the injected gas is equivalent to the volume of the formed pores. The results show that the prepared charge column with porosity defects can be used as the standard test piece for the charge overloading stability test. It has a certain guiding significance for carrying out research in related fields.