Abstract: The aim of this study was to construct a food-grade yeast engineering strain and to evaluate its genetic stability.The prokaryotic gene sequences in the PGZM18,a previously constructed prokaryotic expression vector,was deleted by SOE-PCR;two sets of primers were designed based on the prokaryotic vector sequence of PGZM18,and the fragment sequence was divided into two fragments,P1-1 and P2-1;the prokaryotic DNA sequences(bacterial plasmid sequence,including antibiotic resistance marker Amp,and prokaryotic replication region)were deleted by SOE-PCR;the finally obtained PCR product GZM18 was transformed into Candida utilis,and the genetic stability of the exogenous gene was determined by colony counting and PCR.The results showed that a food-grade genetically engineered strains of Candida utilis was successfully constructed,and the exogenous gene had high genetic stability.Our results provide a scientific basis for application of the engineering strain of Candida utilis in development of microbial feed.