The coefficient of regression is obtained by taking the time scale of 30-year, considering the approximate relationship between the precipitation of Beijing and the temperature of Northern Hemisphere as the linear relationship with the auxiliary variable （the global CO₂ concentration） involved, increasing the gobal variation information, excluding the interference of errors. Then the change in precipitation of Beijing when the temperature of the Northern Hemisphere increases by 1℃ is attained to study the change in precipitation in North China, North-east China and Inner Mongolia. Supposed that the global temperature increases by 3℃ when CO₂ is doubled, the precipitation in regions mentioned above will increase by more than 15 percent. And the precipitation in the’area east of Mountain Taihang will increase by 30 percent.