The invention belongs to the technical field of external psoriasis treatment materials, in particular to a hydrogel medical dressing for the treatment of psoriasis, which is alginate / polyacrylamide interpenetrating network structure water chemically cross-linked with rubidium, magnesium and zinc ions gel. In addition, the present invention also provides the preparation method of the dressing and its application in the preparation of preparations for treating psoriasis. The interpenetrating network hydrogel of the present invention is innovatively chemically cross-linked rubidium, magnesium and zinc ions in the alginate / polyacrylamide interpenetrating network structure hydrogel, through the interpenetrating network polymer and The interaction of the cross-linked rubidium, magnesium and zinc ions has no obvious toxicity to the proliferation of stratum corneum cells, can reduce the expression of inflammatory genes in stratum corneum cells, and achieve the purpose of treating psoriasis.