This document specifies the classification, technical requirements, test methods and storage rules of S standard Cardboard, which is applicable to the production of Cardboard required for the production of precise special molded products and the Encasement of important products. A series of relevant standards are cited, including methods for sample taking, processing and testing under atmospheric conditions, dimensional determination, tensile strength, moisture determination, etc. Standard Cardboard is divided into A and B grades by mass. It is a flat Cardboard with dimensions of 1350mm x 920mm, 1300mm x 900mm or as specified in the order contract. Technical requirements include dimensional deviation not exceeding 10.0mm, deflection not exceeding 10.0mm, and ensuring that the Cardboard has been calendered and the surface is flat and not warped.