The invention provides a technological cavity and a method for judging whether the position of a wafer on a tray is abnormal or not. The technological cavity comprises the tray, a drive unit, and a detection unit, wherein the drive unit is used for driving the tray to rotate. The detection unit is disposed to be at a first preset detection point above the tray, and is used for detecting the vertical distances from the first detection point to all intersection points on the surface of the tray when the wafer carried by the tray rotates through rotating angles corresponding to all intersection points. Whether the vertical distance corresponding to each intersection point exceeds a preset distance threshold value or not is judged. A part, located at a side of the intersection point, of the wafer placed in an installation groove corresponding to the intersection extends out from the edge of the installation groove in an inclined manner if the vertical distance corresponding to the intersection point exceeds the preset distance threshold value. The technological cavity provided by the invention not only can directly judge which edge of the wafer placed in the installation groove is overlapped and which installation groove the edge-overlapped wafer is located in, but also can judge whether an overlapping phenomenon happens in a process that a mechanical arm places the wafer or not.