Hybrid rice combination Longliangyou072 and hybrid rice Shenyou9576 were used to study the yield formation of ratoon crop and its relationship with the main crop. The result showed that among different nodes of Hybrid rice combination, the 2nd node from the top to the bottom showed the highest LAI and dry matter weight and the 4th node the lowest. There was significantly positive correlation between the yield of ratoon crop and the LAI of main crop in tillering stage, booting stage, full heading time and milk stage, the corresponding correlation coefficient were 0.864, 0.896, 0.935 and 0.941. The dry matter weight was the highest in milk stage, and the lowest in tillering stage for main crop and ratoon crop respectively. The dry matter weight of main crop in milk stage was significantly positively related with the yield of ratoon crop (r＝0.451). Comparing to the main crop, root activity and photosynthesis rate were higher while chlorophyll content were lower in ratoon crop. Root activity of ratoon crop in booting stage and full heading time was very significantly positively related with the yield of ratoon crop, with correlation coefficient being 0.913 and 0.843 respectively. Chlorophyll content of ratoon crop in tillering stage, booting stage and milk stage was very significantly positively related with its yield, with correlation coefficient being 0.913, 0.943 and 0.927 respectively. Photosynthesis rate of ratoon crop in tillering stage, full heading time and milk stage was significantly positively related with its yield, with correlation coefficient being 0.722, 0.791 and 0.727 respectively. From full heading time to maturity, the ratooning bud generated from the 3rd node of main crop from different combination showed the largest mean length of bud. From twelve days after the full heading stage to maturity, viable bud rate was decreased along with the nodes from top to bottom. The percentage of 14C photosynthates distributed in panicle was the highest and the lowest in other leaves. The number of effective panicle and seed setting rate affected the yield of ratoon crop mostly, and the 2nd and 3rd nodes from the top to the bottom contributed 70% to the total yield.