The objective of this study was to evaluate the effects of processing parameters of co-rotating twin screw extruder and dry methods on the level of resistant starch (RS) and the properties of extrudate prepared from normal maize starch. The processing parameters were used 90, 110, 130$^{circ}C$ in temperature, 25.0~30.0% in moisture content, 150, 200, 250 rpm in screw speed and hot and cool air drying and drying after refrigerating in drying methods. The barrel temperature and drying methods had affected the level of resistant starch of extrudate. RS levels of extrudates were ranged from 2.4 to 15.5% by AOAC method. The extrudates, extruded at 110$^{circ}C$ and then stored at 4$^{circ}C$, showed the highest level of RS level (15.5%). Water absorption index increased with increasing moisture content and peak temperatures and viscosities of extudates decreased compare to that of raw starch from 94$^{circ}C$ to 50~65$^{circ}C$ and from 220 to 46~98 RVU, respectively. Extudates treated in 90$^{circ}C$ and 110$^{circ}C$ showed strong peak at $2{ heta}=6.7{sim}17.0^{circ}$ by X-ray diffractometry and had ~150$^{circ}C$ endotherm like as that of RS3 starch by differential scanning calorimetry. In case of 130$^{circ}C$, extrudates showed strong peak at $2{ heta}=20.0^{circ}$ and had 106$^{circ}C$ endotherm.