Abstract: Spent fuel storage grid（storage grid）, as one of the important equipments in the storage system of spent fuels, is placed in the spent fuel pool. To improve the storage capability per pool area for spent fuel, plate-like materials which contain some neutron poisons（such as boron aluminum and boron stainless steel） are made into quadrate storage tubes by sheet metal process and welding. The storage grid is usually made up of multiple storage tubes. The thickness of neutron poison plate which influences the safety of spent fuel storage is an important parameter of storage grid and should be measured accurately in the manufacturing process. In this paper, the contact-type measuring method is employed to design the thickness detection system for neutron poison plate by FEMA technological analysis, combining with the modern automatic detection and control technology and database technology. The designed thickness detection system, supporting one button control, can automatically finish the process of thickness detection, recording and statistic for the neutron poison plate, and improving the detecting efficiency and quality.