Abstract: In order to explore the structural characterization and anti-digestion characteristics of mung bean resistant dextrin, mung bean starch was used as raw material to prepare mung bean resistant dextrin by acid heat method. Its surface morphology, crystal form, polarized light, functional groups and glycosidic bonds were characterized, and its anti-digestion characteristics were explored by simulating in vitro digestion. The results showed that compared with mung bean starch, the structure of mung bean resistant dextrin was fragmented with different sizes and irregular shapes. The polarized light cross disappeared, and the chemical groups were similar. The peak positions of each functional group remained unchanged and no new peaks were generated. The crystal structure was amorphous, and the molecular weight M_W of molecular degradation was 5.24×10³ g/mol. The glycosidic bond was broken and a new digestion-resistant glycosidic bond was generated. The simulated in vitro digestion experiment showed that mung bean resistant dextrin had strong anti-digestion ability, and the anti-digestion content was 92.28%. This experiment aims to provide theoretical and data support for the development of functional dietary fiber.