On the basis of introduction of effects of climatic change on ecology and agriculture, the formula to compute related change rate of food yield was deduced by using the temperature and precipitation data of 100 stations in the eastern part of China and according to some empirical formula. The related values of food yield were computed when the yearly mean temperature changes 1, 2, 3℃ and yearly mean precipitation changes 10%, 20%, 30%. The results showed. The yearly mean temperature changes 1℃. The food yield changes 2-3% correspondingly, and the higher the latitude, the greater the effect is; The yearly mean precipitation changes 1%. The food yield changes 1% correspondingly, and it is not change in any where.