Abstract: The purpose of work was to improve the usability of plant-derived selenoprotein and develop selenium-rich foods. In this work,the selenoprotein pectin microgel was constructed by one-step polymerization process using commercial citrus pectin and CaCl₂ as wall material and curing agent,respectively. The best preparation conditions of the selenoprotein pectin microgel were found by single factor tests and orthogonal test using selenoprotein embedding rate as reference. The microscopic morphology,molecular structure,and thermal stability of the selenoprotein microgels were characterized by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR)and thermogravimetric analyzer(TGA). The simulation experiment in vitro were performed to study its digestive properties. Results showed that,the optimized preparing condition for the selenoprotein pectin microgel wtih the selenoprotein embedding rate 66.3%±1.64% was:Pectin concentration 5%(w/v),CaCl₂ concentration 2%(w/v),and operation temperature 30 ℃. The pectin microgel could effectively and tightly encapsulate the selenoprotein and improve its thermal stability. The sustained release of the prepared selenoprotein pectin microgel in mimic gastric and intestinal environments was observed. It showed that the release rate of the selenoprotein in the gastric juice system was only 6.1%,while the cumulative release rate in the intestinal system after 9 hours was 73.6%. The result indicated that the microgel structure could better protect the target protein and control the release rate. The relevant conclusions would provide a new idea for the high-value utilization of plant-derived selenoprotein and the development of selenium-rich foods.