The invention discloses a modularized elevator shaft monomer and an elevator shaft thereof. The modularized elevator shaft monomer adopts shaft units formed by the welding of steel vertical square tubes, lateral square tubes and channel steel, wherein the section of the upper end of each shaft unit and the section of the lower end of each shaft unit adopt a quadrangular structure; the channel steel is fixedly welded between the end parts of the adjacent vertical square tubes; a groove of each channel steel faces the outer part of the corresponding end, namely modular design and modular manufacturing are formed outside the construction site, and the modularized elevator shaft monomer has the characteristics that the structure is simple and the cost is saved; the elevator shaft is formed by connection of the modularized elevator shaft monomers, manufacturing the elevator shaft monomer is completed outside the construction site, and the modularized elevator shaft monomer is formed by the prefabricating of a steel structure, so that after the modularized elevator shaft monomer is transported to the construction site and after hoisting and butt joint are completed, two modularized elevator shaft monomers can be fixedly connected through welding. The modularized elevator shaft monomer disclosed by the invention has the characteristics of being short in construction cycle, quick in butt joint and low in cost, and the phenomena that inhabitants are disturbed by the conventional construction, and the environmental destruction is serious are avoided.