The invention provides a double-pore structure soil pore division method based on fractal theory, which derives a pore fractal dimension calculation method of double-pore structure soil on the basis of a fractal theory according to the characteristic that fractal characteristics of matrix pores and structure pores in the double-pore structure soil are different. Double logarithm processing is carried out on soil-water characteristic curve data to obtain the phenomenon that the pore fractal dimension of the double-pore structure soil is suddenly changed under a certain suction force, and the pore diameter corresponding to the critical suction force value can be used as the critical pore diameter for distinguishing the soil matrix pore from the structure pore in combination with the assumption of graded water loss in the soil. A test shows that double logarithm processing is carried out on a soil-water characteristic curve; the correctness of the theoretical expression of the pore division method is verified, and the contents of the two pores obtained by the pore size division method are slightly different from those of the existing pore division method, so that the defects that theexisting pore division method is complex in form, unclear in critical point significance and inconsistent in results obtained by different methods are overcome.