AIM: To optimize and establish the extraction techn ology of water-soluble polysaccharides from Ulva pertusa. TLC was employed to determine the mainly neutral sugars in the Ulvan. METHODS: The orthogonal test was employed to test the effects of th e four factors including volume of water, temperature of extraction, time of ext raction and pH of water on the yield and total carbohydrate contents of water-s oluble polysaccharides from Ulva pertusa and optimize the extraction technol ogy. Five groups of parallel tests were carried out by the optimum parameters es tablished and the sugar constituents of products were analyzed by TLC. RESULTS: Temperature of extraction and time of extraction have sign ificant effects on the extraction yield of water-soluble polysaccharides from Ulva pertu sa, but, for total carbohydrate content, only temperature of extraction was a significant factor. The mainly neutral sugars were composed of rhamnose, xylose and glucose. CONCLUSION: The optimum extraction technology was A 1B 3C 3D 3 when the yield and total carbohydrate content were considered as preferential pa rameters.