At present, roof greening is an effective way of greening, which has been advocated and promoted as an important part of urban greening. Roof greening can effectively reduce the roof temperature, protect the building layer, extend its service life, and also absorb dust in the air. It can also play a certain role in sound absorption and noise reduction. However, conventional roof greening has not been able to do a large-scale promotion. Major cities have been promoting roof greening by government departments for a long time, but the actual effect is unsatisfactory. Taking Beijing as an example, the promotion of roof greening has lasted for more than 10 years. By 2015, the city has completed about 2 million square meters of roof greening, accounting for only 3% of the total area of all buildings in the city. The low popularity rate is surprising. How about the follow-up of the 2 million square meters building roof which has completed the greening of the roof? It is understood that 500,000 square meters of roof greening plants, due to a relatively single species, poor disease resistance, coupled with inadequate management and maintenance work, later appeared the problem of pests and diseases, soon withered to death, and later the whole piece was eradicated. It is a waste of money to work hard and hurt people's wealth. In addition, there are three difficulties in roof greening: First, there are certain requirements for roof load-bearing. Planting flowers and grass on roofs necessarily requires laying a layer of soil for their growth. If other landscapes are set up, the weight will be greater. But most roofs do not take into account the load needed for roof greening at the beginning of the building, and increasing the load means increasing costs, many developers are not willing to pay such an additional cost. Secondly, the roof waterproof layer may be damaged. In general, the daily irrigation and fertilization necessary for the growth of flowers and plants, if the roof is soaked by water for a long time, coupled with some corrosive substances in the fertilizer, in the long run, it is likely to damage the waterproof layer. At the same time, because the waterproof layer is covered under the soil of flowers and plants, if the formation of leakage, it is difficult to repair. Third, the cost is higher. Not only in the early stage of planting need to spend a lot of manpower and material resources, but also in the later stage need to be regularly maintained by special personnel, the cost is too high. Artificial lawn can be used alone or with some plants for decoration. The amount of soil needed is reduced and the load is reduced. Because artificial lawn does not need to be watered, fertilized and other maintenance, so after laying, it will not cause damage to the waterproof layer, on the contrary, it can also play a protective role. At present, artificial lawn has developed the functions of heat insulation, heat preservation and noise reduction, which makes artificial lawn as the main body of roof greening not only achieve beautification and greening, but also achieve certain functions. Artificial lawn has low cost, simple paving, no need to consider the problems of pests and diseases and late maintenance. It can be evergreen all the year round without management. Its appearance is very close to natural grass, and natural rainwater can be cleaned. Moreover, it has a long service life and is much more cost-effective than real grass. Once popularized, the rate of roof greening will be greatly increased. However, it should be noted that the green roof pavement of lawn must be within the load bearing capacity of the roof of the building, if the load does not meet the standard, then it violates the principles of architecture; moreover, it is necessary to consider roof drainage and wind direction, roof greening should ensure that there are drains, and roof drainage can not be ignored because of the drainage of artificial lawn. The purpose of considering the wind direction is to keep the roof green lawn from being blown down by the strong wind.