Abstract: In order to rapid and accurate determine chlorophyll content of Ulva prolifera,we compared the efficiency of the chlorophyll extractives using spectrophotometer with two different techniques and four extracts,and studied the stability of chlorophyll extractives in four extracts.The results indicated that chlorophyll absorption spectrum was similar in four extracts,accorded with the formula of Arnon to estimate the chlorophyll content.In addition,rubbing technique was better than marinating technique in efficiency of chlorophyll extractives,which was good for rapid determination of algal chlorophyll content.95% ethanol was better than other extracts,but the chlorophyll concentration was less and the stability was worse.