Abstract：Microalgal-bacterial granular sludge （MBGS） process has attracted more and more research interests in the field of biological municipal wastewater treatment. Polysaccharides （PS） are an important component of extracellular polymeric substances （EPS） and one of the key substances to maintain the stable structure of granules. The properties of PS of MBGS were studied. The content， distribution and monosaccharide composition of PS in loosely bound extracellular polymer （LB-EPS） and tightly bound extracellular polymer （TB-EPS） were explored with the potential microbial source of PS in EPS of MBGS. The results showed that PS of MBGS was gelatinous and was mainly distributed in TB-EPS with a content of （40.06±2.30） mg·g-1. Galactose， glucose and rhamnose were the main monosaccharide of PS， while fructose and guluronic acid were not detected. Thauera， Hydrogenophaga， Azoarcus and Acutodesmus were the main potential microbe of PS. The results of this study explained the characteristics of PS of MBGS， providing a theoretical basis for the stable operation of MBGS process.