The work aims to improve the macromolecular properties and stability of sweet corncob polysaccharide (SCP) and promote the intestinal absorption of SCP. The aqueous solution of SCP was prepared into water-in-oil (W/O) sweet corncob polysaccharide nano emulsion (SCP-NE), and the composite protein was used as the wall material to prepare SCP-NE microcapsules. Single factor test, Box-Behnken design and response surface method were used to optimize the preparation process of SCP-NE microcapsules. The physical and chemical properties of SCP-NE microcapsules were studied by particle size analysis, infrared spectral analysis, and thermogravimetric analysis, and the release of gastric and intestinal fluid was simulated in vitro. The optimal conditions for preparing SCP-NE microcapsules were mass ratio of maltodextrin (MD) to soy protein isolate (SPI) of 2∶3, core to wall ratio of 1∶2, total solid content of 20%, and encapsulation rate of (87.6±1.3)%. The results of simulated gastric and intestinal fluid release in vitro showed that the release rate of SCP-NE microcapsules was 8.83% in gastric fluid digestion for 2 h, and 62.87% in simulated intestinal fluid for 1 h. SCP-NE microcapsules prepared with MD and SPI as wall materials have good slow-release performance in gastroenteric fluid release.