Abstract: In this study the effects of Thermus scotoductus 4-α-glucanotransferase(TSαGT) on the physicochemical properties and digestibility of potato starch pastes and gel were investigated. The results showed that TSαGT obviously decreased the content of amylose from 21% to 15% in potato starch, therefore improved the freeze-thaw stability and clarity of potato starch pastes. The potato starch gel property was determinated by instrumental texture profile analysis. The texture property of starch gel with the addition of 0.024-0.06U/g enzyme for 30 min was obviously improved compared with that of unmodified starch. Chewiness, gumminess, cohesiveness and resilience of starch gels were increased, and the gel hardness was decreased. The vitro digestiblity test was executed according to Englyst method. The results indicated that the modification with less than 0.024U/g of TSαGT for 30min, improved the anti-digestiblity of potato starch. The reverse effect was obtained in the modification with too more TSαGT. Therefore, modification of potato starch by TSαGT in suitable conditions significatly improved the physicochemical property and anti-digestibility of starch gels.