Abstract: Our "three in one" research group studied the effect of gibberellin on the yields of rice in many experimental plots for several times. We raised the yield of rice by 5%–10% by treatment with gibberellin at late growth period of rice. Amount of gibberellin applied was 20 ppm for early season rice and 30 ppm for late season rice. We studied the effect of gibberellin on the growth dynamic of stems, leaves and panicles, the change of photosynthesis and respiration rates, the rule of translocation, distribution and accumulation of materials in various above ground parts. We also studied the dynamic of grain filling, the rate of oxidative phosphorylation and the activities of the enzymes of starch synthesis and starch hydrolyze during grain filling period. Base upon the above mention ed results, we explained the high yield theory basis of gibberellin treatment.