Soil - bag hydroponic culture was conducted together with ordinary soil pot experiment to study the relationship between rica oranging physiological disease and Si, Fe in red soil solution. It was found that compared with red soil solution without rice plant, Si/Fe of that with rice plant decreased while Si/Fe of soil-bag hydroponic culture increased. Electron probe analysis showed that the soil pot treated rice root had very high Fe peaks in outer cell wall of epidermis while very low or none Fe peaks were found in soil-bag treated rice root.Thecause for Si/Fe rising of soil - bag treatment and its role on correcting the physiological disease were discussed.