Abstract: Sunflower flower disk differentiation is the key determinant factor for sunflower yield. The correlation between the differentiation stage of flower disk and the foliar age index and using the foliar age to predict the flower disk development are pivotal for promoting the flower disk size, increasing the flower seeds amount and facilitating the high yield of sunflower. Our data suggested that the sunflower flower disk development could be classified into six stages：the pre-differentiation stage of flower disk-the differentiation stage of flower disk- floret differentiation stage-stamen and pistil differentiation stage-ovary ovule differentiation stage- pollen differentiation stage.The foliar age index was around 24% just at the pre-differentiation stage of sunflower disk;it reached to 45% at floret differentiation stage and 48% at stamen and pistil diffentitation stage and69% at ovary ovule differentiation tage;it increased to 86% at pollen differentiation stage.