In this paper, the design process of the four-legged steel trellis column is introduced for an actual project. The internal force calculation including of axial pressure and bidirectional bending moment are discussed. The strength and stability satisfy the requisition by code. Confirm that the stability of sub pillar is key element for design of trellis column. The simulations show that the design method is safety and reasonable by STAAD.pro software. Different gridding is chosen based on length, width and thickness of members; excess larger or smaller gridding is improper. The conclusions and methods can be referred by later engineering.