Recently, based on the shapes and structures of Hangeul letter forms found in old literature, the number of fonts currently being developed that are suitable for use in a digital environment is gradually increasing. However, in this process, “old” Hangeul, otherwise known as “old language,” is often excluded from font development. Nonetheless, it is clear that font development—including old Hangeul—is absolutely necessary in order to convert documents from the past into a database. This study was designed to propose a direction and mechanism for designing fonts suitably matched to the structure of old Hangeul letter forms. To this end, Hunminjeongeum Haerye (1446), Hunminjeongeum Eonhae(1459), and Hunmongjahoe(1527), Draft for a Unified Korean Spelling System(1933), were first reviewed to define the concept of old Hangeul and examined the composition, structure, and arrangement principles of old Hangeul. This study then examined how the coding system for inputting old Hangeul in the digital environment changed through 11 fonts developed using the standardized input system, which is the syllable-initial-peak-final encoding process to find problems with the approach. Next, based on literature review and case studies, the researcher proposed a combination structure classification for old Hangeul fonts in order to address the aforementioned problems. Lastly, to check the effectiveness of this suggestion, Unicode—which is used in the syllable-initial-peak-final encoding approach—was applied to the combination structure of old Hangeul fonts based on the classification that was first proposed by the researcher. It is my sincere hope that this proposal will contribute to the design of old Hangeul fonts as an alternative that complements the shortcomings of the existing syllable-initial-peak-final encoding.