Abstract: This experiment concerns with the preliminary studies of seedling root's growth, protein content, respiratory intensity and G₆PDH, IDH, PK, three respiratory enzymes of hybrid rice Shanyou 36 and its parents. The results of the experiment are shown that the growing amount of root of Shanyou 36 is larger than that of its parents and the respiratory intensity lower. On the characteristics of respiratory metabolism, there is higher IDH activity in female parent Zhenshan 97A and higher G₆PDH activity in male parent IR36. In the hybrid Shanyou 36, the PK activity is higher than that in the parents, but its proportion in the total activity of three enzymes is between that of the parents, so are the proportions of the other two enzymes. It is put forward that the turnover state of EMP pathway, represented by PK activity, and the relationship among EMP, TCA, and HMP, the three main respiratory pathways, may play an important part in the formation of the heterosis of the root growth in hyb rid rice.