Abstract: Polysaccharideof Gracilaria lemaneiformis was extracted with hot water and sedimentated with ethanol.And then the content of polysaccharides was determined by anthrone-sulphuric acid method and phenol-sulphuric acid method, in order to compare the difference of these two methods. The linearity of the phenolsulphuric acid method (R2=0.9992) was 20⁸0μg and anthrone-sulphuric acid method (R2=0.9993) was 10¹00μg. At the same time, the result of phenol-sulphuric acid method had good stability, reproducibility and sample recovery with 99. 76 % ~ 99. 97 % and RSD was 0. 22 % ~ 0. 25 %, which was better than that of the anthrone-sulphuric acid method. In conclusion, both the anthrone-sulphuric acid method and the phenol-sulphuric acid method could determine the polysaccharide content of sample. However, the result of phenolsulphuric acid method was more reliable and accurate, it could be considered as the optimum assay method for polysaccharides in Gracilaria lemaneiformis.