With the development over time, people and the government gradually realize the importance of the environment. From 1962 to 2021, the forest coverage of Saihanba increased from 13% to 80%. This article used the AR model to establish time series from three aspects: oxygen release, carbon dioxide acceptance and water source storage to analyze the ecological environment before and after Saihanba ecological protection action. In addition, a time series of air quality in Beijing was established to show that the environmental improvement of Saihanba has helped reduce the dust weather in Beijing. After that, AHP analytic hierarchy process model was used to evaluate the significance of altitude, temperature, wind force, humidity and precipitation for the establishment of ecological areas. China is divided into four regions according to the differences in geographical environment. The demand degree of ecological areas was evaluated for these four regions, and the areas that need established ecological areas were selected. Then the scale of the ecological area of the site was determined through the best benefit and cost evaluation. In conclusion, based on the ecological environment construction mode of Saihanba, this report established a model that can be used to evaluate the ecological environment benefits and the best implementation site.