The invention discloses a method and device for determining an aggregation and reservoir forming coefficient of a heterogeneous reservoir and a storage medium, and belongs to the field of oil-gas exploration and development. The method includes the steps: determining a median depth of the heterogeneous reservoir; determining the lower limit of the reservoir forming porosity of each single lithologic reservoir in the heterogeneous reservoir according to the median depth of the heterogeneous reservoir; determining the lower limit of the displacement pressure of each single lithologic reservoir in the heterogeneous reservoir according to the lower limit of the reservoir forming porosity of each single lithologic reservoir in the heterogeneous reservoir; and obtaining the lower limit of the displacement pressure of the heterogeneous reservoir according to the lower limit of the displacement pressure of each single lithologic reservoir in the heterogeneous reservoir. The aggregation and reservoir forming coefficient of the heterogeneous reservoir is determined by the lower limit of the displacement pressure of the heterogeneous reservoir. The method can determine the aggregation and reservoir forming coefficient of the heterogeneous reservoir, and, compared with a mode of judging the difficulty in aggregation and reservoir forming through the lower limit of the displacement pressureof the single lithology, the method improves the accuracy of the judgment result.