This research studies how a rain coat (兩衣) had developed in ancient China by searching through historic records. It can be said that people in ancient China wore two kinds of rain coats: straw coat and oiled-cloth coat (油衣). Straw coat was originally used in the Spring and Autumn and Warring States period. Then, people used natural grasses to make it. As the overall production had increased, various kinds of rain coats began to appear in Tang (唐) Dynasty, and the straw coat itself became elaborate. In Song (宋) and Yuan (元) Dynasty, the straw coat was used for the army, and when it came to be Ming (明) and Qing (淸) age, wearing it was considered a symbol of hermit. The straw coat shows the early form in the history of clothing, which was mostly put on by the poor. The material for straw coat was the grass which grows up in wet land area. People in the city and in the country had worn the straw coat for a long time. As foreign cultures were introduced, however, it disappeared first in cities and later in the country. The oiled-cloth coat was another of the kind. Its major material was water-proofed silk in the Qin(泰) and Han(漢) Dynasty. Also, it was a favorite of an emperor or aristocrats. Common people put on straw coat until the time the western rain coat was introduced and accepted in Qing Dynasty.