This article investigates the functions, needs, and developments of the MARC format for classification data. and recommends the development for the KORMARC format for classification data. It ae analyzes the record structure, content designation and the content of it mainly based on USMARC format. Structure and content designation are almost same with those of the bibliographic and authority formats. The data fields divided into functional blocks based on their functions. Record contents of the data in the fixed-length fields include more elements on the classification numbers, including type of number, classification validity, standard or optional number, synthesized number. Variable fields can be grouped into several blocks, inducing those for numbers and codes: for classification numbers and terms; for references and tracings; for notes fields: for index terms fields, and for number building fields. Data in each fields of this format have the same contents with those in other related fields as soon as possible. This article analyzes the content in each data fields in detail.