Effect of silicon on chlorophyll a,chlorophyll b and total chlorophyll contents of rice seedlings at different position under cadmium stress were studied by hydroponics culture method.Rice seedlings were treated with the concentration of 4.0 mg.L^-1Cd²⁺and 0,30,80,130,180 mg.L^-1SiO₂.The results showed that three chlorophyll content in the 5th and the 4th leaf from the top of rice seedlings under cadmium stress increased when the concentration of silicon was 30~130 mg.L-1 SiO₂,and they were the most at 130 mg.L-1 SiO₂.The chlorophyll a,chlorophyll b and total chlorophyll contents of the 5th leaf from the top increased 189.47%,38.66% and 75.93%,and that of the 4th leaf from the top increased 161.15%,166.23% and 177.61% compared with cadmium stress.When the concentration of silicon was more than 130 mg.L^-1SiO₂,the chlorophyll content of the fifth and the 4th leaf from the top decreased.The three chlorophyll content of the 3rd leaf from the top increased with the increase of SiO₂concentration.When the SiO₂concentration was 180 mg.L^-1,the three chlorophyll content were the highest（2.5239,0.8120,3.3359 mg.g^-1.FW）.The effect of silicon on three chlorophyll content of the 3rd,the second and the first leaf from the top of rice seedlings under cadmium stress was less significant than on the 5th and the 4th leaf from the top of rice seedling.