Abstract: To study the effects of calcium on photosynthetic characteristics and the subcellular distribution of rice, the high-calcium in brown rice cultivars and low-calcium in brown rice cultivars were used for test. Rice plants were grown in hydroponics system to study the effects of 0.0, 0.5, 1.0, 5.0, 10.0 mg/L Ca² on photosynthetic characteristics and its subcellular distribution in two different types cultivars. The results showed that the photosynthesis of high-calcium in brown rice cultivars was higher than that of low-calcium in brown rice cultivars. The calcium concentrations in leaves were higher than that in roots system. Ca² was distributed as follows cell wall > ribosome and the fractions of soluble component > plastid (or chloroplast in leaf) > the fractions of nucleolus > mitochondrion. Ca² was mostly distributed in cell wall and less distributed nucleolus and mitochondrion. Ca² concentrations were increased with increasing of Ca² treatment contents, especially more significantly in high-calcium in grain cultivars. Because the Ca² increase with the increase of Ca² treatment contents in the important organelles in high-calcium in grain cultivars was much higher, the ability to absorb Ca² may be stronger than low-calcium in grain cultivars.