In this paper,waxy corn starch was treated by pullulanase and generated many starch chains of different length,and then recrystallized at low temperature to produce slowly digestible starch(SDS).The paper mainly studied the effects of enzyme concentration,recrystallization time and debranching time on the formation of slowly digestible starch,and analyzed the properties of corresponding SDS.The results showed that,under the condition with pullulanase concentration 20ASPU/g(dry starch weight),debranching time 6h,standing at 4 ℃ for 3d,SDS content percentage reached the maximum at 21.26%.The total content percentage of SDS and RS reached 36.68 %.The crystalline form of debranched and recrystallized starch changed from A to V-type crystal.The To、Tp、Tc of the obtained SDS were increased,which indicated that the prepared starch samples have a firm structure and a good thermal stability.