At present, the development of cities is very rapid, and the products of industrialization in cities occupy most of the urban space. The balance of harmonious coexistence between man and nature has been broken. The earth's ozone layer is gradually being destroyed by greenhouse gases. As we all know, plants can consume carbon dioxide to produce oxygen. Therefore, my idea is to plant plants as much as possible in free places in the city, such as the roofs, outer walls, and balconies of buildings. Turn a white city into a green city.