This paper reviews the structure of horse armor. Identifying the structure of horse armor is not an easy task because horse armor was completed by connecting hundreds of lamellar pieces. Due to this, the study of horse armor has been relatively limited but it must be noted that the study of its structure is a key element for stimulating research on horse armor. Examples that can reveal the original form of horse armor have recently been discovered, such as the example from Jjok-saem C10. Utilizing such information, an attempt to restore the structure of horse armor is made in this paper. Firstly, classification was undertaken by examining the shape of the lamellar pieces and the arrangement of their holes. Based on the results, commonly observed lamellar combinations were established and identified as the typical lamellar composition. It was possible to reconstruct horse armor shape by analyzing the results of excavation. By identifying the presence or absence of horse armor for the different body parts, the structure of a suit of horse armor could be established. Through the study, it was possible to confirm that there four main types of horse armor were used during the Three Kingdoms Period. As each type demonstrated regional characteristics, they were referred to as ‘Busan-style’, ‘Okjeon-style’, ‘Gyeongju-style’ and ‘Magapchong-style’ Horse Armor. The different types of horse armors seem to have shared production techniques.