Based on the special chemical characteristics of betaines and their analogues, ion-exchange chromotography was selected to extract and separate them from marine algae. Dragendroffs reagent(KBiI4) was used to test the existence of betaines and their analogues in marine algae. The total content of betaines from seven species was obtained by using the sediment method of Reinkeate salt. The result shows that the content of betaines in two species of Chlorophyta and two species of Rhodophyta are relatively high, the content of betaines in Enteromopha prolifera can even to 0.9%. The content in the three species of Phaeophyta is relatively low The total results obtained by above methods will be great value to determine how to exploit and ultilize betaines and their analogues in marine algae.