Abstract: An inverse microemulsion was prepared with distilled water as water phase，n-hexane as organic phase，and Span 60 mixed with Tween 60 as emulsifying agent and n-pentanol as co-emulsifying agent. The dextrin nanosphere was then prepared with the inverse microemulsion by using Na3P3O9 as cross-linking agent and dextrin as raw material. The results showed that the emulsifying agent was in positive correlation to water solubility, whereas n-pentanol co-emulsifying agent was in negative correlation to water solubility in the system of inverse microemulsion. The cross linking reaction taking place successfully was confirmed by infra-red spectrum analysis. A uniform dextrin nanosphere with a diameter of 500—600 nm was measured with scanning electronic microscope.