In this paper， the physicochemical properties and digestibility of waxy rice starch(WRS) and oat-β-glucan (OBG) complexes prepared at different freezing ball milling times were investigated， and the physical and chemical properties and digestibility of the complexes prepared at different processing times were characterized and evaluated by scanning electron microscopy， infrared spectroscopy， rheometry and simulated in vitro digestion. The results showed that with the increase of the freezing ball milling time， the surface of the complex particles became rougher and the shape of the particles became more irregular， with agglomeration and agglomeration. The infrared spectral results showed no significant changes in the individual absorption peaks and no new chemical bonds were formed. The freezing ball milling treatment caused the OBG to mosaic or attach to waxy rice starch through hydrogen bonding， and the relative crystallinity of the complex decreased from 29.72% to 8.62%， and the short-range orderliness also decreased gradually. At the same time， the content of the double helical structure of the complex decreased and the content of the amorphous region increased significantly. The peak viscosity and regeneration values decreased from 931.00， 103.33 cP to 159.33， 41.00 cP， respectively， with the increase of freezing ball milling time， and the values of consistency coefficients K， G′ and G″ decreased， enhancing the fluidity and stability of the system. In terms of digestibility， the complexes prepared by freezing ball milling were less digestible than the native waxy rice starch. When the ball milling time was 60 min， the maximum resistant starch content of their complexes reached 35.92%. This study provides new research methods and technical tools for starch processing and modification.