Abstract: Stability and rheology characteristics of CMC/milk protein/sucrose phase separation systems influenced by different concentrations of κ-carrageenan (0, 0.025% and 0.05% w/w) was researched, aimed to probe the internal mechanism of the improvement caused by addition of κ-carrageenan in CMC/milk protein/sucrose phase separation systems. Significant microstructural differences of different phase separation systems were detected by laser scanning confocal microscope and addition of κ-carrageenan could scatter aggregated milk protein effectively and preserve uniformity of products thus improving phase separation behavior. Results of rheology characteristics showed that κ-carrageenan could greatly enhance pseudoplastic behavior and stability of frequency independence of dynamic modulus, theixotropy was enhenced by synergy effct between κ-carrageenan and CMC to casien. Moreover, the percentage of large particle size also increased by the action of κ-carrageenan, which demonstrated that stability of CMC/milk protein/sucrose phase separation systems were influenced by the formation of network structure of gels and the presence of synergy effct betweenκ-carrageenan and CMC greatly.