The invention discloses a method for predicting vertical well volume fractured reservoir reform volume of low permeable reservoir. The method sequentially comprises the following steps: (1) calculating the induced stress produced by hydraulic fracture in a three-dimensional space; (2) calculating the formation pore pressure obtained after leak-off of fracturing fluid; (3) calculating the formation pore elastic stress obtained after the leak-off of the fracturing fluid; (4) overlapping the stress fields obtained in the step (1), (2) and (3) with an in-situ stress field to obtain a new crustal stress field, and calculating the magnitude and direction of three-way principal effective stress in the overlapped reservoir space; (5) calculating the open fracture determination coefficient M of a natural fracture in the reservoir space and the shear fracture region determination coefficient S of the natural fracture so as to predict the volume fractured reservoir reform volume. The method is used for predicting the reservoir reform volume after vertical well volume fracturing, is better in operability and accuracy, provides a favorable theoretical basis for effect evaluation and yield prediction after vertical well volume fracturing of the low permeable reservoir, and overcomes the defects of the prior art.