Standards are the scientific basis and an important factor for the assessment of the quality of goods. In International Sale of Goods Law, they are consistent with and complementary to the “general provision” on “ordinary purposes” used to assess the quality of goods. Based on analyses of theories and legal practices and by reviewing the relationship between standards and “ordinary purposes,” in this article, I attempt to find out what standards affect the ascertaining of “ordinary purposes” and present a summary of the preconditions for the sellers’ obligatory observance of such standards to provide guidance for the accurate application of other “general provisions” through the use of standards.