Disclosed are a mixed porous structure interbody fusion cage and a preparation method thereof. The interbody fusion cage comprises a porous metal support and porous structure filling bodies, the porous metal support is a three-dimensional net-shaped structure, a plurality of holes are arranged in the porous metal support, and the porous structure filling bodies are fully filled in the holes. The preparation method includes steps that the metal rapid forming technology is directly combined with the freeze drying technology, the porous metal support is manufactured via a structural design and the direct metal rapid forming technology, then uniformly mixed polymer gel or polymer/ biological ceramic compound gel is poured in the porous metal support to realize freeze treatment, so that the porous structure filling bodies with the micropore feature are formed after freeze drying, and the mixed porous structure interbody fusion cage is obtained. Mechanical compatibility is good, contact area between the mixed porous structure interbody fusion cage and natural centrum is further increased, instant stability is good, fusion rate is improved, and the mixed porous structure interbody fusion cage and the preparation method thereof can be used for treating clinical degenerative disc diseases.