The invention discloses a method for quantificationally calculating fracture porosity by an array acoustic logging porous medium model, and belongs to the field of reservoir assessment. The method comprises: firstly establishing a pore aspect ratio spectral distribution function, and determining pore distribution regions; then adding pore aspect ratio spectra distribution into an equivalent medium model, establishing the array acoustic logging porous medium model, establishing a target function by combining a rock modulus of array acoustic logging calculation, obtaining the morphological characteristics of the pore aspect ratio spectral distribution through an inverting manner, and quantificationally calculating the fracture porosity by using a fracture cut-off value. The method for quantificationally calculating the fracture porosity by the array acoustic logging porous medium model, provided by the invention, can be applied to conventional sand shale reservoirs, and can also be applied to fracture effectivity assessment of complex reservoirs, such as complex lithology reservoirs, buried hills and the like; quantitative calculation on the reservoir fracture porosity is realized, and reliable fracture parameters are provided for the reservoir assessment; the method has become an important technology for reserves evaluation, and the reserves evaluation accuracy is improved at the same time.