In order to figure out morphological and anatomical structures of double grain sorghum and its development process, improve the morphological and anatomical theory of sorghum, and explore cytological mechanism of forming process of double grain sorghum, double grain sorghum ISD-1 was used as material, and the ovary and anther development processes were observed with the traditional paraffin section method. Through cytology study on the female and male gametophyte development of double grain sorghum, it found that the pistil base of double grain sorghum fertile flowers of sessile spikelet grew into two different sized cavities. A spacer layer was between them, there were three anthers and an ovary in each cavity. The development of small and large cavities was in no particular order. The ovules, megasporogenesis, anther development and microsporogenesis were out of sync in two cavities. Anther development was different from traditional form. Anther first developed into one or two pollen sacs, and then the pollen sacs integrated into one complete anther. Compared with single grain sorghum, there were some distinct cytological characteristics in double grain sorghum. This study initially revealed that the reason for double grain sorghum formation was its pistil was divided into two cavities, and these cavities had complete structure of anther and ovary. The study is of significance to optimize the morphological and anatomical theory of sorghum.