Abstract: To solve problems of the cold-rolled steel sheets such as the tensile testing standards are not unified in the international, the percentage elongation after fracture (A) is affected by the specimen gauge length creating no direct comparability and conversion limitations, also to meet the requests that the automobile steel sheets of the same stamping level should adopt the percentage elongation of the same standard reflecting mechanical properties proposed by automobile body designers, this article proved that there is no relationship between the percentage total elongation at maximum force (Agt) and the specimen gauge length by the test. According to the status quo that Agt can be measured by tensile testing machine, it was advanced that Agt should be included in the table of the mechanical properties for the standard of automobile steel sheets.