Abstract: Resistant dextrin (RD), a low-molecular-weight soluble dietary fiber, is traditionally produced through pyrodextrinization via acid-thermal treatment of starch. However, conventional methods are often limited by high energy consumption, prolonged reaction times, and suboptimal yield and resistance. To address these challenges, this study introduces cold plasma (CP), an innovative green physical field technology, as a pretreatment to enhance the conventional acid-thermal process for producing resistant dextrin from waxy maize starch. The primary objectives were to optimize preparation conditions to improve yield and to systematically characterize the structural, physicochemical, and rheological properties of the resulting product. Waxy maize starch was pretreated using a dielectric barrier discharge plasma system under atmospheric air. Single-factor experiments were conducted to evaluate the effects of plasma generation voltage, plasma treatment time, hydrochloric acid dosage, acid-thermal treatment time, and thermostable α-amylase hydrolysis temperature on resistant dextrin yield. Subsequently, an orthogonal array design was employed to optimize the process parameters. The resulting resistant dextrin samples—with (CP-CRD) and without (CRD) plasma pretreatment—were analyzed for solubility, whiteness, freeze-thaw stability, and rheological behavior. Structural characterization was performed using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and proton nuclear magnetic resonance (¹H NMR). Under the condition of a high-temperature α-amylase hydrolysis temperature of 94 ℃, the optimal preparation process was determined as follows: plasma generation voltage of 80 V, plasma treatment time of 90 s, hydrochloric acid concentration of 12%, and acid-thermal treatment reaction time of 60 min. Under these conditions, the yield of CP-CRD reached 83.12%, significantly higher than that of the control (72.60%). Physicochemical analysis revealed that CP-CRD exhibited significantly improved solubility (96.66%), along with enhanced freeze-thaw stability, as evidenced by smaller reductions in transmittance across multiple freeze-thaw cycles. Rheological tests showed that both CRD and CP-CRD displayed shear-thinning behavior; however, CP-CRD exhibited higher elastic and viscous moduli, indicating strengthened molecular network formation likely due to plasma-induced cross-linking and incorporation of polar functional groups. Structurally, SEM images revealed increased surface roughness and granule fragmentation in plasma-pretreated resistant dextrin. XRD and FTIR analyses confirmed complete loss of crystalline structure in both dextrins, with CP-CRD showing a more pronounced amorphous content and a higher R_1022/995 ratio. ¹H NMR analysis indicated that CP-CRD contained a lower proportion of α-1,4 glycosidic bond (36.68%) and higher levels of α-1,6 glycosidic bond (20.91%) and β-type linkages (β-1,2 glycosidic bond, β-1,4 glycosidic bond, β-1,6 glycosidic bond), along with an increased number of reducing ends. These structural changes contributed to a higher average degree of branching (42.18%) and a lower average degree of polymerization (3.32) in CP-CRD. In conclusion, cold plasma pretreatment significantly enhances the efficiency of acid-thermal treatment conversion of starch into resistant dextrin. The synergistic mechanism involves plasma-mediated depolymerization, generation of short-chain fragments, surface microstructural modification, and introduction of polar groups, which collectively promote more frequent and random glycosidic bond rearrangements and transglycosylation reactions during acid-thermal treatment. This leads to a final product with higher yield, improved solubility and freeze-thaw stability, and a more highly branched, complex structure enriched in digestion-resistant linkages. This study could provide a theoretical basis for the development of a green and efficient preparation process for resistant dextrin based on plasma-assisted technology.