Abstract: Taking terminal buds of different developmental stage of Tagetes erecta L.‘Scarletade’as materials，the flower bud differentiation process，micro structure and ultra-micro structure of flower organs were studied by using morphological observation，paraffin section and SEM and TEM. The results showed that：（1）The process of flower bud differentiation starts from the two-leaf period to three-leaf period，and from outward to inward，the developmental stage is closely related to morphological changes.（2）The structure of the stigma of the flower changes from bar-like to Y-type and finally to curved Y-type，there are plenty of papilla structures covered the surface，the stigma became curved Y-type after pollination and wizened papilla structures.（3）There are two pollen sacs in mature anthers，which were separated by connective tissues. The mature pollen sac wall is composed of flat epidermal cells and fibrous layer.（4）The pollen are prolate，ellipsoidal in equatorial view and nearly spherical in polar view，with 3 germinal furrows，and there are many spines of different length，with the average of 4.65 μm，on the exine. The equatorial axis length is 37.5 μm，and polar axis length is 25.5 μm.

Key words: Tagetes erecta L., flower organ development, micro-structure, ultra micro-structure