The present invention discloses a semicrystalline polymer/graphene oxide composite film, comprising: a first semicrystalline-typed polymer, distributed in structural space of the composite film and having a porous structure; and graphene oxide, having a layered structure and distributed in the composite film wherein gas passage exist between adjacent layered structures, the first semicrystalline-typed polymer existing between part of adjacent layered structures forms into a second semicrystalline-typed polymer by further heat treatment after the first semicrystalline-typed polymer and graphene oxide are blended uniformly to be distributed in the composite film so as to fill and seal a portion of the porous structure to block gas from flowing to extend path length(s) of gas passage; wherein graphene oxide existing between the first semicrystalline-typed polymers induces formation of the second semicrystalline-typed polymer.