The invention provides a layout structure used for simultaneously detecting process windows of multiple bottom contact plugs. The layout structure comprises a plurality of first metal layers and a plurality of second metal layers, wherein the plurality of first metal layers are electrically connected with test pads, the plurality of first metal layers are transversely arranged at the same interval, and directions and feature sizes of the first metal layers are the same as that of a phase-change material layer; and the plurality of second metal layers are electrically connected with active regions, the second metal layers arranged outside the central position of the layout structure are isolated from one another, and directions of the second metal layers are perpendicular to the directions of the first metal layers. According the layout structure, the process windows of the bottom contact plugs can be detected comprehensively and effectively, and the reliability of the process can be improved.