.The process for the desaltation of the polysaccharide from the mixotrophic liquid culture of Nostoc flagelliforme with radial flow chromatography (RFC) column packed with Sephadex G-100 gel was investigated. The RFC column having 7.7 cm of bed length and 229.6 cm3 of bed volume was used in this study. The effects of some operating factors such as the sampling weight, the flow rate of eluent on the desaltation efficiency were examined. It was found that the separation efficiency increases with the decrease of sampling weight and flow rate of eluent. With 2.4 mg of sampling weight and 0.3 ml/min of flow rate of eluent, the salt content of polysaccharide was lowered from 90.42% to 2.36%. As a conclusion, this technique can be used to get rid of the eluant in the polysaccharide introduced by the ion exchange process.