American writer Mark Twain has witnessed changes of American environment of the 19th century, which changes his sense of place. Urbanization and industrialization separate human beings from nature, leading to various conflicts. City is always regarded as the symbol of order, reason, crime and degeneration, while nature means freedom and happiness. Twain advocates the return to nature to lead a simple life. He tries to reveal the ecological crisis in the 19th century and express his ecological concepts through redefining “place”, “space” and son on.