Sweet potato was one of most important food crop in the world which has a great source of dietary energy, in the form of carbohydrates. This study was carried out to investigate the appropriate conditions to produce high yield of sweet potato starch using commercial cellulase and determine chemical composition of the isolated starch. The optimum enzymatic conditions for improving sweet potato starch extraction were found to be 3 U/g of concentration of cellulase, ratio of water and sample 150ml/100 g sweet potato at 4 h of incubation time. Chemical composition of isolated starch with enzyme-assisted isolation was not significantly different from starch using without enzyme. The results show that sweet potato starch treated with cellulase only enhanced yield of isolated starch with high purification.