According to the characteristics of forestry and agriculture and the feature of
agroforestry system on slope in the hilly
region of Sichuan Basin, the internal structure of
agroforestry system was systematically studied, and the positive and negative effects of the forest belts to the crops were investigated. On the basis of analysing the distributing pattern of the scattering radiation, the feature of water and soil loss, the distributing pattern of the yield, and the distance between two forest belts on slope, the distance between two forest belts on slope which shoud be no less than three\|fold average height of forest belt has been provided in a position to guarantee against decreasing yield. Meanwhile, a contrastive analysis on the synthetical
efficiencies of agroforestry system model and agriculture system was finished. The results showed that the productivity was improved, the energy transforming ratio, and the utilization efficiency of nutrient, value and labor force were also increased in agroforestry system on slope. It was provided with the more great producing potential.