Underarm opening sleeves and pendent sleeves have a common wearing characteristic, namely both of them hang behind the shoulders, but they have differences in terms of shape and structure. Underarm opening sleeves and pendent sleeves, with strong identification and vitality, prevailed and were widely transmitted across ancient Eurasia. They have attracted close attention from scholars and can both be traced back to Kandys of ancient Persia, a kind of cloak with two pendent sleeves. This paper aims to explore the transmission paths and features of underarm opening sleeves and pendent sleeves in ancient Eurasia, costume culture of clothes with underarm opening sleeves and pendent sleeves during the process of transmission, and the formation cause of the shape of underarm opening sleeves. From the holistic view this paper summarized the past findings and sorted out the historical photographs, literature, and heritages to explore the evolution of Kandys and clothes with underarm opening sleeves. The research shows that in ancient Persia, Kandys had important functions of religion, politics and culture. On one hand, it was used as ritual clothing for sacrifice; on the other hand, it was used as honor clothing to indicate the noble status and identity. As an important cultural sign, the pendent sleeves of Kandys which appeared on the figures of empire king, priest and Anahita and were used to be the saint clothing in the scenery of divine right of kings, were inherited and developed in the Persian Empire system. With the population migration and trade activities in ancient time, as a signal, the clothes with two pendent sleeves were transmitted to East along the Silk Road and ritual and honor were still the dominating factors of costume culture to be transmitted during the process. Sogdians and nomadic people were the prime transmission medias. In the process, the cultural characteristics of pendent sleeves were gradually endowed with multiple characteristics of nationality, Xianbeilization and Nomadizing. Clothes with pendent sleeves were practical for nomadic people, and were further transmitted by them. Clothes with underarm opening sleeves appearing around the 7th century A.D. resulted from the colliding and merging of two mainstream culture Byzantine costume culture and Sassanid Persia costume culture at that context along with the rise of Islamic civilization. The underarm opening sleeves with the joint image features of Byzantine costumes and Persia costumes became the Byzantine military uniform style and were very popular across Eurasia. In the Yuan Dynasty (1271-1368), the clothes with underarm opening sleeves called “Hai Qing Yi” were worn by Mongolian. The popular style of clothes with underarm opening sleeves was mainly transmitted through the two medias of European Crusaders and nomadic people, who jointly promoted bidirectionally dynamic transmission between East and West. During the long process, underarm opening sleeves were gradually endowed with decorative characteristics. The long-term evolution process fully manifests the blinding of Eastern and Western costume culture and multicultural characteristics of clothing shape. The continuous evolution of pendent sleeves and underarm opening sleeves consists of a series of “conjunctures” and “events” resulting from cross-era and cross-regional collision and exchange of civilization and culture. Meanwhile, the long term, conjunctures and events jointly promoted the evolution of clothing shape and exchange and transmission of costume culture between East and West. The paper systematically collected, combed and analyzed the evolution process of the shape of pendent sleeves and underarm opening sleeves, expanded the time and region and explored the transmission paths and features from the perspectives of trade activities along the Silk Road and migration of nomadic people, thereby enabling the process of development and change of clothing shape and blending phenomenon of Eastern and Western costume culture to be more clear. [ABSTRACT FROM AUTHOR]