Resistant starches（RS） with high RS content were prepared from mung bean starch respectively via the autoclaving treatments with and without the addition of pullulanase.Then,the effects of the starch slurry content,the enzyme dosage,the debranching time,the retrogradation temperature and the retrogradation time on the formation of RS were analyzed,and the granule morphology,crystalline structure and thermal characteristics of the starch were investigated by means of SEM,XRD and DSC,respectively.The results show that（1） after an autoclaving treatment at 121℃ for 20min,debranching with 50ASPU/g pullulanase at 55℃ for 24h and a storage at 20℃ for 24h,the RS content of the sample was 56.9%;（2） after the debranching and recrystallization,the recrystallized starch granules display irregular shaped fragments,the XRD pattern changes from Type A to Type B,and the degree of crystallization greatly increases from 17.9% to 45.7% in the presence of enzymatic treatment;and（3） the melting temperature,the enthalpy and the thermal stability of RS all increase after debranching and recrystallization.