This paper aims to study the modern characteristics of Robert Frost's natural poetry, which are distinguished from romantic natural poetry, focusing on the relationship between humans and nature in his poems. Frost did not participate in experimental poetry movements conducted in the early 20th century and mainly dealt with human life in nature and rural settings with spoken language and traditional rhymes, putting his poems on the boundary between 19th-century romanticism and modern poetry. On the one hand, the harmony between man and nature or the spiritual comfort and happiness seen in some of his early poems made him called a traditionalist or regionalist who inherited the literary tradition of the 19th century New England. However, many of Frost's poems are distinct from 19th -century romantic poems in that they portray nature as a world that has its own laws of life separate from human ones. Frost depicts existential speakers who try to fulfill their social responsibilities as humans by enduring the pain and solitude of life in front of nature, which is beautiful but dangerous, without transcendental beings or gods. This study shows the fact that Frost's natural poetry inherits British romanticism and American transcendentalism in the 19th century, but reflects the modern perception and attitude of nature that do not appear in them.