The invention belongs to the technical field of gene engineering, and particularly relates to an escherichia coli gene engineering bacterium and a method for producing L-threonine by using the escherichia coli gene engineering bacterium. The gene engineering bacterium is characterized in that a promoter P of phosphoenolpyruvate carboxylase gene (ppc) of an initial strain is replaced into a promoter P of 6-phosphate dehydrogenase gene (zwf), so that the goal of regulating the L-threonine production capacity by glycine betaine is achieved. In the fermentation process, the glycine betaine is added, so that the L-threonine yield through shaking flask fermentation can reach 50 to 55g/L; the 5L fermentation tank yield reaches 120 to 150g/L; the saccharic acid conversion rate reaches 59 to 61 percent.